[LowGT]

If it were my truck, I think the best option would be to leave the frame alone, spray the bed sides satin black, and put the siding like luvbowties mentioned. I think it looks better than plywood and doesn't cost much more. You should definitely be able to pull that off for less than $100 and a Saturday.

The truck is definitely too nice to sell as-is. Someone will use the missing bed as a big bargaining chip. $100 is a good investment even if they plan on ripping it out later. At least they can't say, "I'm going to have to put a bed in it and that will cost blah blah much."