Your suitcase is either going to get beat up or stolen, so why drop a fortune on it?
I fly quite a bit, and regretted buying a budget suitcase a while ago .... I think it didn't even last ten flights before the shell had cracked.
Simple. Buy quality, buy once.
The last three posts really narrowed in on the conundrum ... rugged quality that will last for a lifetime ... the thief's lifetime, that is ... or a Walmart Special that nobody would be bothered to steal, unless they were interested in used duct tape. I guess the key is to buy a sturdy case that isn't theft-bait.