I read thru all this and after 2 years of 912 ownership I would suggest that you not even consider purchasing a car for 3000. There are stories of people paying less than that and maybe a few of them have had enjoyable ownership experiences. But the reality is that these cars are VERY maintenance intensive, parts can be expensive, and you need to ask yourself if you are willing to spend the time required to get a $3000 into shape so you can drive it and enjoy it.
The other question is this - if you have an engine problem, the spare parts situation - especially cylinder heads, bearings, cranks, and a few other things - is such that you can easily spend $3000 on a "cheapie" engine rebuild - and then have to do it again 5000 miles later because there was a problem. It HAS happened. Do you really want to put that kind of money into a car with obvious rust issues ?
By far your best strategy is to buy the best car you can possibly afford, so you have something that's worth fixing AND you can take advantage of the generally rising market value of these cars. Good examples can be had for $8000 if you look around. I would say April is the WORST time to buy - that's when the pre-summer prices are highest.
I paid 10 grand for my car and I've put about that much into it - rebuilt engine, suspension, brakes, etc. It's a delight to drive but requires constant tinkering. Parts are expensive and are likely to get more so, because of the increased popularity of the 912 and late 356 Porsches that use the same engine.
There are a few exceptions but in general if you only have 3000 bucks to play with, consider something else because a 912 at that price will not be good enough to make you happy. After you've spent $4000 on your $3000 car, you'll find you need to spend another $5000 to turn it into the car you really should have bought in the first place...
http://www.petry.org/pics/babe9.htm
Just my opinion...
Mark Petry
Bainbridge Island, WA