Auto parts stores carry R-134a kits that cost between $15-30. My 98' SLK 230 no longer puts out cold air and I'm tempted to try it. Am I biting off more than I can chew? Should I just take it into my mechanic?

Thanks!

If you don't know how much refrigerant is already in the system you may end up ruining more parts than what is wrong or broken by overcharging the system. Take it and get it diagnosed and an estimate for repair.

Usually, A/C shops would charge about $100 to test the system and charge it as well if there is no leak found. at the same time they will put in the dye for the leak to be found. Tha'ts for the indy shops. The dealer in NJ charges $199.
But I would recommend getting it done professionally for just another 50 or so dollars. This way the leak can be found and you wont have to buy the freon again incase it leaks away. The cost at the shop would cover refill of freon most of the times.

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Yeah, thanks for the advice guys. I suppose it'll be worth it to throw in the extra cash given my current skill level and equipment. I've found a good mercedes mechanic who should be able to take care of me.