Other Brand Batteries for DSLR's

Has anyone got any experience with batteries that are not the original manufacturers ones. Basically I need a spare rechargeable battery but I looked at the Olympus ones and they are between £44 and £77 in some places,
I can get another brand for between £10 and £15, so are these other brands any good or would they be a complete waste of money ?

Cheers,
Mark.

Koa, I have 4 e-bay batteries for my 40D and they have performed perfectly well. You get 2 for about a tenner instead of the £30 a pop for the Canon stuff. Never heard of anyone having problems with them either in any of the forums I frequent.

www.7dayshop.com

between me and my dad we have 7 of the third party batteries from there

Thanks a lot guys, I just ordered a couple from that link, £5.95 or something, can't go wrong with prices like that

i have 2 batteries for my D80 that i got from ebay for £7 each and their great., they actually outlast the standard nikon battery and ive been using them for about 6 months now with no problems.,

Nice,
It's unbelievable how much the prices differ for things like this, someone's taking the P by the looks of things.

you'll always get that with batteries! Just look at car batteries from a main dealer then at the prices from a decent interweb supplier