Jared - In Illinois (or there abouts) $4k should get you a running truck, or a truck body that is mostly restored.
I just brought home my 58 for $1800. It has not run in 15 years (though it was not stuck) & being from Arkansas there is very little rust - thought the cab corners & doors have started.
Now mines a 58 4 head light & the 57's are more popular so they will bring a little more, but unless the body is close to perfect I'd be talking him down a little.
Check out eBay & see what they are selling for. That will give you a good idea what you should be spending.
Also check out the trucks for sale here - again these will be pretty fairly priced.
