I have picked up 2 in the last 18 months from my local O'Reillys. It may or may not be the best/cheapest option, but it is the only place near me that always seems to have a Miata AGM in stock when I need it.
Apparently my battery died suddenly after 4+ years. Stopped to get gas and the sucker wouldn't start after that. Luckily I had a buddy following me and we were able to push start it, Karate Kid style...
I'll get the meter on it in the morning to confirm battery death, but where's the latest local place to get a decent Miata battery? I got this one at O'Reilly a while back... it's an AGM, yadda yadda...
'94 Black & Black & Tan
'99 head swap, JR header, TDR intake & header blanket, MegaSquirt, RB hollow bar, Tein Flex, 15x8 6ULs, HD M2 Sport, FM cat, Borla cat-back, black '95M interior, MOMO Zebrano, IL Motorsport console...
Dyno Days
8/16/08 (bone stock): 103.1 hp/99.0 lb-ft - Dynojet
8/23/08 (Borla cat-back): 108.2 hp/104.1 lb-ft - Dynojet
8/13/11 (more stuff...): 126 hp/116 lb-ft - Mustang dyno
Roger Moore: the Danny White of James Bonds
I have picked up 2 in the last 18 months from my local O'Reillys. It may or may not be the best/cheapest option, but it is the only place near me that always seems to have a Miata AGM in stock when I need it.
+1 on the O'Really's AGM. Just bought one about a month ago.
Trickle charge it, it may be good.
+1 on O'Reilly. Mine died (O'Reilly) didn't have a reciept, not sure how long I had it, I think TDR picked it up and installed it a few years ago while it was there, but I took in in any they just swaped me out with a new one. Didn't even look it up. Cool. Guess it pays to be a regular customer (like I have much choice living in the sticks).
I have a load tester and a trickle charger if you need it.