For your stated goals, you definitely don't need sways or LSD. I would agree with Cal that you should still consider the Koni FSDs though. By all anecdotal evidence, they will deliver a better ride over cracked pavement, even if you don't care about the improved cornering.
I'll read between the lines: you listed more power as last, and said you just wanted a "little." Given that it's a low priority for you, and your low budget, I'd say forget about tuning the engine. Your money would be better spent on good rims and cosmetics, the stuff you'll really use and notice every day.
BMW CCA Member