New batery for Mercedes 500SL

MB 2005 500SL uses 2 batteries . One on the engine compartment and another on the rear trunk. I have replaced the one on the back but now the one in the engine
compartment is finished. Dealer wants $270 can $ for that small battery . It is much smaller that the other one. More like a motorcycle battery. Must I payed that much for a small battery only because is made in Germany?
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