I looked for about three years before finding mine, but I was really picky about what I was going to buy. It had to meet quite a list of criterea:
1. It had to be $1,500 or less (I'm not rich and didn't want to pay for things I would change anyway).
2. It had to be a Dodge (My favorite make).
3. It had to be a B200 w/6,400 # GVW (H.D. 3/4 ton w/less smog equipment).
4. It had to be a Tradesman model (didn't want to pay for Sportsman interior I wouldn't use anyway).
5. It had be 109"WB (like the look of "shorty" models and don't need extra WB).
6. It had to be 6-door model (slider door wouldn't work w/ planned mods).
7. It had to have no windows in cargo area (windows wouldn't work w/ planned mods).
8. It had to be a 1977 (newest year for my favorite van body).
9. It had to have a rust-free floor/frame (needed to drive immediately
and wanted good, safe foundation for build).
10. It had to have V8 and TF trans (didn't want to have to find/buy/swap drivetrain before begining build).
Since you are in no hurry, I think you will be much happier in the long run if you just hold out for what you really prefer. P.S. Check out this place, they specialize in cargo vans (they are in SE Portland):
http://www.cargo-vans.com/listings.cfm/Category/Cargo_Vans