Used is a good option look for a redfield or leupold, I have seen some great prices on M6's used on ebay before they are an excellent scope(fixed). I still have one and it has never had a problem.

I have heard good things about swift but no personal experience. I will say Bushnell seem to deliver a reasonable scope I use the elite series and have been always happy, I would consider them to be mid range but an affordable quality scopes-however they may be higher than what you want to spend. I know many who use the trophy series by bushnell and a couple guys who bought the new legend by bushnell, no real complaints I have heard of either yet.

IMO your better to save and buy something that will last, then just buy another cheap scope that you'll replace soon. If your scope now is functioning fine but you just want a bit better, than save up and buy one you'll really enjoy later.

Good Luck!