First, I don't think you will find a refurbished unit. You will find OE and aftermarket. I have used them and they work well once connected. The connection is a little more work with the aftermarket, but if you do it yourself, you will save enough money for the fuss of the aftermarket part.
If your tech does it, you are at his mercy on parts.
I use only the Behr or the ACM cores on the really hard ones, but on the 190, the evap is so easy to get to, I'd use any of them within reason.
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MERCEDES SPECIALIST 11 YRS