Re: 1990 e250 2x2 (kicking myself?)
If you've got a 10k budget, I'm not sure I'd overextend myself on this one. While the low miles are attractive, the fact is that it has been doing a lot of sitting over the last 25 years. If you are mechanically inclined, then replacing hoses and belts isn't too big of a deal. However, you may be looking at another $1k if you took it to a shop for a 'tune up' to get everything current (unless it was done by the previous owner).
Whether something is a bargain is also correlated to exactly what you are looking for. If you really like that particular layout and have an affinity to the old body style, indeed it may have been worth jumping on. Some folks don't mind a project to modify and clean up a few things; others want to start with everything the way they had envisioned. YMMV.
2009 Express AWD, CCV Top & 50-ish home build. Daily driver/camper/kid hauler