If you're looking for price try K mart or Wal Mart. If you're near Pontiac, go to Boaters World at Summit Place Mall on Telegraph North of M-59 to check on their prices. They're alot better priced on things than either West Marine or Boat US. I just picked up 3 Sears Die Hard Deep cell's for $85.00 a piece.
I swear by gell batteries. Have tried everything during my 35 years on the lake and have been using them for the last ten years. They are pricey but they last longer than conventional batteries. I have one installed right now that is starting season eight. They're generally around $150/$175 but they last and take the pounding you can get on LSC.
I like Wal -mart batteries for my boat and vehicle. I think I paid $55 for my last one. I think the MRC is 850, the RC 120. I would never buy a Sears die hard. Many bad experiences. As for the gell previously mentioned, I guess it depends on how many years you get out of them. The Wal-mart battery will last 4-5 years. Multiply that by 3. You get 12-15 years, and spend $165. Good luck with whatever you buy