Pelicanparts has a lot of the consumables and I'm sure there are other sources, too.
IMHO the "best" version if you want to go NA is the S2 (or a 968) - displacement bumped up to 3L with a 16V head, with the second best version being the rare-ish 2.7L 8V. The 2.5L ones aren't what you'd call torquey (in both 8V and 16V guises) and make the car feel a little gutless unless you rev it.
The 16V system is a bit weird with the timing belt driving one cam and a short chain driving the other one - IIRC there can be issues with the chain tensioners that can lead to broken chains or chains that skip a tooth, both resulting in expensive valve salad.
The other expensive job is a clutch replacement due to the mountain of work involved so unless you don't mind spending a weekend under the car to replace a clutch, I would try to buy one that already has had the clutch replaced.
Parts prices in general aren't GM-cheap but they're noticeably cheaper than parts for a 911.
Sanity is vastly overrated.