Absolutely right about the batteries, they're just darn hard to find online, Apple won't sell those for unibodies. I don't live in the States but I come by once in a while, and for reasons not worthy of explanations here, purchasing various replacement parts online (or any other electronics for that matter) is by far my best choice.
I have just replaced the battery in my MBP a few days ago through an Apple consultant, who charged me double for doing the job in a few hours (as opposed to 7 - 9 days that I couldn't afford, at any Apple store/service). The one before that got depleted in less than 2 years (but just about 900 recharging cycles).
My first PowerBook lasted me 5 years until dropped in a lake. This MBP is almost there too (reaching 5 years, not in a lake hopefully), and with a spanking new OCZ Vertex4 SSD and new battery, it feels like new, and I really mean that, especially after trying a few of the newest "low-end" MBPs at the store. I always agreed with..."if it works, don't fix it (or get a new one)".