I bought the biggest freakin battery I could find at Advance Auto! (uh, biggest in CCA, not physical size) I want to say it is 800? 900? I dunno, I'd have to look - but I remember the prices got funky - they went up as the CCA's went up, but then dipped near the top of my selection choice to a bit cheaper.

CCA = Cold Cranking Amps.

I paid around $80-85 for it after the core charge. (old battery exchange)