i got a walmart battery for $35. it's covered for 1 year, no fault and it's cheap enough to replace every 2 years for peace of mind.

i'm running a pretty decent sized system off of it and the battery is fine. also, the fridgid conditions outhere really tend to kill and stress batteries too

if you have the loot for an optima, go for it ... if you're strapped for cash, go the cheap route.