I just "rebuilt" (repacked is more how I think of it) the 1984 Stronglight BB on my fixed gear bike this morning & took it for a ride. Wow...big difference, nice spin! I've been told from the C&V folks this was high quality stuff when new & I guess all I can say is that the gamble I made on this fugly fubar'd '84 Peugeot wasn't too bad after all because cleaned, lubricated & installed correctly the original headset & BB turned out OK...very OK! I'd never had to do (or, maybe I should say 'bothered to do') BB service before & with the right tools it was extremely simple. My point is if you can get mileage out of what you have (or have lying around), why not do it & put some miles on the bike so you can have a better idea where you want to throw the next $60.

That said, if you open yours up and it's all pitted, corroded, or whatever, then you're in the market for something, whether its' $20 or $60.

EDIT: if you're paying someone to do it, buy new, sealed, high quality stuff so you won't have to pay someone again any time soon.