How much would it cost for an electrical problem in my car to be fixed?

My car's battery has been dying on me two times already and this is my third time buying a new one. It seems that all the lights of my cars air conditioner/ heater turned off and its giving me difficulties to cool the a/c. Only the fan works and when you live in florida, you need more than just a fan to keep cool in this heat! I know the cooler is filled with freeze on but it's still not letting me function anything on my controllers, hence not cooling at all and it is giving off a really bad smell. It's a miracle actually that my radio is still working.
Also both fans are working just fine.
Can someone please give me an estimate of how much it would cost me to fix this? I'm guessing its some wire problems that is running my battery dry…

Please and thank you.

P.s. I forgot to add that My car is a Honda Accord SE 2000.

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