I have been experiencing the same problem. I put my battery on a tickle charge overnite and it has been starting fine, but I think I am going to buy a battery anyway. I did do allot of checking the forum and some shops around here and this is what I came up with if you need it in the further.

Firestone has a MTP H6 with about 640 CCA which from what I understand is the same battery that the dealers sell. Firstone sell it for about $160.00 give or take.

Firestone also sell a MTP 91 with about 700 CCA for about 115.00. It will fit into the battery mountly plate.

PEP Boys sell a Bosch 48-690B for about 100.00 the will work also, it has 690 CCA.

Sams Club sells a model # E48 it has 700 CCA which I understand will work also. The cost is 67.00 and installation is free. I forget what the brand name is, but it has the 3/96 warrenty that I was looking for also.

Hope this helps.
Larry