Alright got a bit more time so I will go into a bit more detail:
Regarding costs for something something like this - It's all down to how well you want to do it... invest too little and you have a poor product, invest too much and you've blown your budget that you need for marketing.
To make the front end well you would want it ajax like googles own, you could use jquery and cut a few corners. Obviously for google every byte counts and I guess you could do it on a basic basis to begin with.
With the back end you would need a good database system but its likely you could do it with mysql or similar. Twitter have actually provided a lot of information about how their databases work. I think they even gave out their full system details which would be hugely useful for an engineer.
Obviously the more sites you crawl, the more storage and servers you need. As for your spider, this isn't my area but I imagine it would cost a fair bit for a developer to do.
I think you could sort of 'bootstrap' this with the amount you have specified, but it just seems a bit too much, especially when you don't have experience in this area.
Why would someone pay to be featured if un-featured sites can be voted on too? Unless the feature gives them more exposure so they can get more votes... However this would be close to pay for results and could be seen very badly.
So how do you stop black hats manipulating the votes by using proxies and automation software?
I think I understand what you're saying - It searches comparison sites so people can find the best comparison site for the product, and it uses user feedback to position the sites.
However, why would someone choose you instead of using google product search, or visiting kelkoo or similar?
Clearly you do and I commend you for having this much to potentially invest, however I would seriously advise you to stick to what you know.
About 2 years ago I was hired by a firm who had fucked up hugely with their project. Not just a little bit... hugely. They had taken investment from friends and family of over £500,000 and created a website with little knowledge about web design.
They build it in ASP, it was ugly, it didn't function properly, it wasn't popular and it sunk.
In the end they lost their friends money, they lost their investors who had trusted them money and they lost their other business too.
The reason that they crashed is they didn't take good advice, they threw money into it without solid direction and without the knowledge they needed.
I would recommend you starting on something small but similar to get a feel for this kind of project.
Perhaps your own comparison site which crawls the web for good prices on something specific?
First of all, thanks for all the detail.
"Why would someone pay to be featured if un-featured sites can be voted on too? Unless the feature gives them more exposure so they can get more votes... However this would be close to pay for results and could be seen very badly."
This is a valid point that I'd thought about before hand; to expand on what I'm saying: the featured sites are always "better then adverts", and probably going to be better then a retailer site - criteria would be a comparison-based site, so they'd be practically the same thing as the un-featured search results. Secondly, all searchs start at 0. When featured, you go straight to the top - but if a user clicks on second and "likes" it, then you go to second. the idea is, featured sites get more exposure to both liking and visits through entering the top few pages. Featured sites fit into the search at a ratio of around 1/3, or so, and get shown for votes. The only main difference between featured & un-featured is that featured sites have more exposure to visits, but have to pay for this. There should be no dislike for featured sites, because each would be individually checked to make sure its as good as the rest of the results - a comparison site - so really, all featuring does is get visits (targetted!) for a comparison site, and doesn't really effect the viewer. I have made a (very quick) image:
Features like, for example, the page total, and the blue text, would mainly be inserted if the site was a success.
"So how do you stop black hats manipulating the votes by using proxies and automation software?"
You need to be logged in, and can't vote more then twice (on two different sites), per user-account, neither can you vote more then 5 times per hour.
To sign up you need to fill in a capt, but again, this login system wouldn't be in place till the site became popular enough for the featured feature - it doesn't really need it before hand, and, if the voting system was applied to results, it wouldn't matter if they were spammed - they don't earn any money, and it would hardly effect the web master / be worth doing if it was unprofitable to feature your site.
"However, why would someone choose you instead of using google product search, or visiting kelkoo or similar? "
Why do people use affiliate link based comparison sites?
because these offer reviews, and most importantly, comparisons between products. You go to a affiliate-link based comparison site, you get a page or three, prices, indepth study - you look at product description on google product search, you will never get comparisons, or more then 5 sentence long descriptions. For this reason, people like comparison sites - thats why it'd be great for them to have a trusty hub to find them with. I think its a market gap.
I understand your comments about only really being able to "bootstrap" - but with nothing else to compete with, bootstrapping is enough until revenue is a possibility.
In similarity, I can see the situation to do with this firm - However, my initial stake here does seem to be fairly low, and, though losing £x,xxx, is a lot, I do think its worth the risk, especially if marketted right. For example, if you want to compare ... light bulbs ... which page would you rather be confronted with:
10 sites with light bulbs for sale, with no comparisons, no real security, nothing really detailed, and 3 or so adverts - or - 10 sites which compare light bulbs, which give you price comparisons, value for money, what costumers think, maybe even talks about energy-saving light bulbs in comparison, etc, etc... I'd pick the latter.
I will consider and post my thoughts and the site if it ever goes live - thanks to you all.