Nah it's all good about the other thread, you're asking where to buy batteries so that's cool
3 yrs eh ? Getting anything beyond 18 mths is pretty good assuming you're charging it at least a little once per day (if you're doing a full charge/discharge you'd get less than that), and even if you're not doing that (say charging only every 2nd day), two years is pushing it.
You've done well to get 3 yrs out of it. I mean, you could get BetterBatteryStats & see if there's wakelocks/whatever causing drain that you might be able to reduce, but everything you've said points to a simple case of the battery being on the way out, so a replacement is probably the go.
If it's important enough to cause you grief if it's lost, back it up. No excuses
Trolling for thanks is lame
Does Samsung's auto-brightness implementation crap drive you to self-harm ? A solution !
Failure to search is the leading cause of male impotence on XDA
If you don't know how to recover if things go wrong, what are you doing flashing custom roms ?