It's funny, you can't wait too long or someone will get it, if you snap it up you might sit and there and think why? It depends what you're buying for, people on these forums all have a foot in domaining but it might not be their main thing.
The best with a domain is high traffic, previous website, good engine placing, good overture results for keyword in the 50,000 to 100,000 mark and good ov with extension, as well as brandable and a top keyword helps and a past, current or future market alongside a few other pointers.
How many of those you wish to encompass will denote your spend on setting up but you can start any way you want, it's your money, just think about it before you do, I did think a little but then I didn't really have to much as I bought brand domains, a lot of which I will brand myself.