I don't know if I can comment on what is "best", but I urge you to make sure that wherever you buy from, the RAM is guaranteed to work. I purchased RAM from a local reseller, and had to return it twice (caused kernal panics in my powerbook). Since then I have purchased RAM from CanadaRAM (online) for a few Macs - prices seem quite reasonable, good customer service, and most importantly, if it doesn't work it can be returned (and they all worked without any problems).