if you have a flea market near, you can look there too. I got mine for $1.00 (one). It was used as a battery back up for an alarm in a house. It is about 5 inches tall 6 or 7 inches long and 3 or 4 inches wide. it is a gel battery so it wont leak. mine is 7 amps. I only charge it about 1 time per month and I use it for my fuel pump, 12v starter, and field charger.

Good luck.

One more thing. If you get one of the 12v hand starters from the hobby shop, be sure not to use a battery over 50 amps. you will burn up the starter after a while. Most of the starters say on them or in the paperwork that comes with them what them max amp rating is.