4 weeks and didn't find a perfect one.
i was lucky, i was always going to buy my best friend's one, but decided i'd have a look around and see if i could get one cheaper as his cost a fortune...it was immaculate to say the least.
anyway while i was looking i called up over 12 people, saw 5, got 1 mechanically tested, and not one of them was worth it. i was annoyed the one i had tested was not 100% because from my tests of it i thought it was.
that said, i was trying to buy cheap, as i already had an expensive one lined up, so i wasn't exactly looking at ones advertised for any more than low 20s.

you think buying an s2000 is hard? try buying a dc2r. i don't know what the market is like now, but 2 years ago heres how it went:
1 isn't a type r
1 is a write off
1 doesn't have recaros any more
1 doesn't have log books
1 has crazy sounds coming from somewhere that the seller claims he can't hear (no joke)
1 is missing parts you'd probably want a type r to have
none of them are white (except the written off one)
and then, after searching one pops up you're happy with, you verbally agree to buy it on the day you saw it come up, it sold 45 mins later with a "sorry i can't believe i had that much interest i should have asked for more". i've looked at a lot of cars, different makes and models, and have never seen one sell in 45 mins.

the only part about buying a dc2r that was easier was i could tell from advertisements and pictures what sort of condition the car was in, whereas s2000's i had to physically see.