Replacement A500/2000 rechargable batteries

[TjLaZer]

I have a A501 card and was wanting to get a new battery for it.  I could go the NiMh route, or do the lithium hack.  But what I want to do is get a rechargable lithium battery that will fit in the same spot.  Anyone know of any?

edit:  I would love to get a hold of a few of these!

http://cpc.farnell.com/BT01218/batteries-power-supplies/product.us0?sku=MAXELL-ML2032-T25

Thanks!