a 30mm stem is probably going to make your ride twitch as ****. a slight shift in handlebar direction with a 110 or a 100mm stem is one thing, but you have to consider how much more of a turning angle that produces with a way shorter stem.

most people don't ride such short stems because it really, really screws with your stability.

i've ridden a couple different bullhorn setups and my favorite is with a burly, burly nitto mtb stem with nitto pursuit bars (the ones with a drop to them). the stem is a 90mm.

the cheap, low end stems are really flexy and make me super nervous. you're gonna get a lot of flex out of those nashbar bullhorns as well. its not really a big deal if you don't weigh a whole lot, but it's certainly not fun.