I'll second Victorinox. Everyone knows what an SAK is, and a lot of people buy them who wouldn't buy a "real knife." Add to that, they're affordable, and of very high quality. You could charge a reasonable ammount over wholesale and make a good profit.
Queen is a good idea for the old fashioned looking knives. Not as affordable, and ultimately not as useful to non-knife people, as an SAK, however. But they're still high quality, nice knives.
Buck is also a good option, but when you get into the locking knives you need to be up to date on your town's knife laws. Locking knives are illegal in some places, and Buck makes assisted openers now that could be considered autos by some ill-informed police officers/judges.
I'd start with Victorinox and if it's successful and you feel like branching out, then move onto Queen, Buck, Case or Camillus.