For as much trouble as keeping a guitar in tune can be, it seems kind of masochistic to go in search of the lowest priced parts available. Not that high prices equate with quality, but in a free market that's usually how things work because competition keeps most manufacturers/suppliers honest.
I've used a lot of different tuners, and given a choice these days I always pick the Sperzels, although I'm going to try the Schallers on the next build. In any event, if you disregard issues of style and performance, you're probably only going to see $10-$20 spread between the various offerings. So, the more pertinent question would be "which tuner works the best for the longest time?"
Unfortunately, the answer there is "all of them". Like many parts these days, it's tough to get bad ones. The worst of the lot are pretty good, unless you go out of your way to get some old vintage crap.