Keep in mind that there are three different red-top Optima batteries. The $99 battery at Costco I believe is the lesser of the three. They are:

Optima 34, #8002-002: CCA 800 amps, MCA 980 amps.
Optima 34/78 dual, #8003-003: CCA 800amps, MCA 980 amps.
Optima 78/35 dual, #8022-091: CCA 720amps, MCA 910amps.

Personally I prefer the 34/78 dual. I run the truck off the side posts and the winch off the top. I recently saw Optima Red Tops at Pepboys. Seems the price was good, and no membership needed.