I bought my 2100 mAh NiMh batteries on ebay over a year ago. The brand is Digital (never heard of it) and since they weren't expensive and the seller had a good rating I bought them. It came as a package with batteries and another no-name charger. They still work great, and when I added more I just bought the same thing - even less at that point because they weren't the highest capacity. I didn't know if there would be a problem with different brands or capacities in the same charger, so by getting the same ones, I eliminated that possibility.
I'd recommend getting one level lower than the highest capacity out there, maybe it's 2300mAh. The current biggest/fastest/best always costs a lot more for not much more performance.