These are the same battery configuration used in popular micro RC aircraft like the Eflight Blade MCPX and others. Any hobby store that carries RC models will have them in various capacity and C ratings. As far as chain stores go, Hobby Town USA has them. They run $5-6 dollars in the store but are typically higher dishcarge rated then the ones you see online for $1-2. There are many brands available. You can also go with a larger mAh capacity battery for longer life but realize it will have larger dimensions and you will want to make sure it still fits in the space you have alloted for the battery.
Also, you can buy connectors from vaious vendors to make your own wiring harnesses e.g. for charging or, with the Raven, for powering the altimeter if you are not using the PowerPerch or Featherweight AV bays. Here is what I ordered to make a charging harness for use with my existing chargers and for powering when the PowerPerch is too big.
Mouser 538-51047-0200 Molex 2 position housing
Mouser 538-50125-8000 Molex terminals
You solder the terminals onto your wires and then press them into the housings. You can also find premade pigtails on some of the hobby websites.