Wow, I hope some of the earlier posters were being sarcastic about the 3/4 ton mumbo jumbo. Find a 1/2 ton that you like and that is in your price range and get it. Problem solved.
I do agree with the advice about avoiding mid-sized trucks (ie, V8 Dakotas) and smaller motors, though. The midsized trucks are not often any more efficient than the full-size 1/2 ton, but lack capacity. For example, our Durango got worse mpg than our Suburban AND had less capability than the 'Burb has. All of the drawbacks, none of the benefits, in a sense. I suppose the one benefit of the Durango was a few thousand less $$ at purchase (which is how we got sucked in), but we regretted it for the next 3 years -- it didn't tow very well, had less space, generally wasn't as smooth or nice, and got 11 mpg around town/17 highway (with the 4.7 V8). FWIW, I would almost put the '02 Tundra in the midsized group. It was a little smaller, underpowered w/ the 4.7, and had far lower ratings than 1/2 tons of that vintage.
Likewise, the 1/2 tons w/ the smaller V8's wont usually get much better, if any, mpg, but they just have less power when you want it. See my experience with the Dodge 4.7, above -- our GM 5.3s have gotten better mpg with a lot more power. Similar anectodal experiences from people I know who went with the 4.x liter GM or Ford engines in 1/2 ton trucks. They regretted their decision.
Good luck!