Some neighbors of ours a couple houses back bought an old moving truck for their cross-country move; they didn't re-sell it, though, and actually haven't bothered registering it in-state yet, it's just parked in a storage lot.
When my husband and I did a cross-country move a couple years ago, we rented a moving truck (I didn't even think of buying and re-selling one), and even now that we've seen neighbors buy one and use it, I'm not sure I'm gutsy enough to do that. We got a good deal on a Penske truck (I think it was around $1300 to go FL to CA with their largest size truck, plus a car trailer and their insurance package that covered any and all damage done to the truck/trailer). The truck we got was almost brand new and it was nice knowing we didn't have to worry about the past maintenance or anything like that - we could just pack up and go.
We had some luck getting the price down by price-matching different companies against each other (Penske, U-Haul, and Budget). Based on online reviews we'd seen, we knew we wanted to go with Penske, but we used the other companies to knock at least a couple hundred off the price.