Don, if you got an older laptop with no waranty, it should'nt be a problem, if your seller has good references, and you can't find negative feedback regarding the battery exploding, catching fire or having a short life span/not holding a charge or short power on time after charging; I'd say go for it...

Some of the aftermarket batteries are better than the factory ones.... What is the name of the company that produces the batteries you are looking at?