Which motor? Rust? Body damage?
3k does seem like a decent price... but it'd leave lots of money for repairs and a build. My 97 E350 Type 3 Ambo with a 7.3 has 200k miles, 16k hrs... we're coming on 3 years with only an alternator, brakes, TREs, ball joints, springs, and minor work related to the engine. It may seem like a lot... but 95% of the work needed to be done at the time we bought it, and was part of why we got it for about 1k USD. It now handles, rides, and drives very well. It is a real pleasure to drive, and I'd not hesitate to drive it across the country.
All that said, a pickup and a custom camper from
http://www.idacamper.com/ (or someone similar) might be a good option for you. On a flat deck, chasis, in the box... it could offer the best of both worlds.
As much as I love my Ambo, van engine bays suck. That said I drove a newer F350 Ford supercab, and it was a beast to drive and I wouldn't want to own one.