I was once in your shoes. I had a nice a/e ovation to be exact but just a crappy Ibanex RG electric. I thought by getting new pickups I would be able to revitalize the pathetic tone. Well to a degree you can but the problem is the wood the guitar is made out of generates or at least contributes a significant amount to your tone as well.
I went with a EMG set two SA single coils and one 81 humbucker, it set me back around $220 but came with two tone controls a volume and 5 way toggle switch. The tone was drastically better than the stock, like light years better. The only problem was the guitar itself sucked.
Finally I realized it wasnt just the pickups but the whole guitar that sucked. So I bought what I am playing currently a Fender 69' thinline reissue telecaster. You could probally find one for around $450 on ebay maybe $550 but it sounds alot better and is a beautiful looker I highly recommend it.
I ended up selling the Ibanez with the awesome pickups for $275 which was a good deal to the fellow that bought it. So if your set on getting new pickups definitely buy EMG's they are the best no quesiton about it, however I'd recommend another guitar first and would look on ebay it hasnt let me down yet!
What type of music do you play?