These days $2000-$3000 will get you a somewhat running PDP8/e/m (SSI/MSI); the 8/a is much cheaper ($1000) as its processor is LSI.

DANG! Even three or four years ago the '8 would have fetched over $1000, easy.

As an owner of a real PDP8/m, I can assure you that spare parts are available. The beauty is, you can actually troubleshoot down to part that can be purchased off the shelf; today's systems are fixed by board swapping, lest you waste your time finding out the problem is in some custom IC. Of course, I'm not sure anyone does that kind of troubleshooting anymore :(