If it's possible, I'd think about moving into the Purple Widgets business or shelling out for the .co.uk.
Getting UK search results on a .net or .org is not easy without a lot of work and it taking forever, so if you're actually going to develop something where the focus is on search performance I'd go for the org.uk and the hyphenated .co.uk.
Sure you give away visitors, but you'll do that whatever you pick unless you have the .com and .co.uk. I really don't think that the typical domainer created site is the sort of thing people type in anyway, as most revenue comes from links and search. Is "Blue Widgets" likely to be a type in domain in the .co.uk do you think?
FYI, by way of an experiment I set up sites with good search volumes on .co.uks versus .nets and .orgs and months later the gTLDs are still precisely nowhere on Goog UK, even after setting the geo location to UK in Goog's Webmaster Tools, whereas the .co.uks set up at the same time are performing well - eg search
pet carrier on Goog gives PetCarrier.co.uk at #3.
Obviously just an opinion, but hope it helps. Even though domains are cheap, development isn't. If you do go for the net, I'd say buy the others and use a UK one later in a quick rebrand if the .net doesn't perform and 301 the net across to it so you don't lose the indexing.
Regards
Ty
Bit of a dilema. Want to buy a domain to develop ( possibly later resell ) but have choice of (pretending domain is bluewidgets ):
blue-widgets.co.uk
bluewidgets.net
bluewidgets.org.uk
Would you buy a hyphenated .co.uk or a non-hyphenated .net or .org.uk
Website will be 100% UK focus and any potential resell target would be UK too.
I am leaning towards the hypenated .co.uk or non-hyphenated .net but looking for opinions?