Any Recommendations on Parts Suppliers?

[trojannate]

Recently, I bought a Mass Air Flow Sensor for my 2001 Audi TT coupe. It was through a distributor on Ebay. I put the part in and it made no difference in my car's performance problems. I took the car in a month ago for tests and they verified that the MAF sensor was in fact not operational.

I don't know if it was somehow caused to malfunction by my car, or if the original part was bad. But to avoid the same problem, I wanted to write and ask for any recommendations on parts suppliers who could sell me the MAF sensor with a warranty/guarantee. I don't mind buying online as long as they are reputable. I will have the part tested by a mechanic before being placed in the car this time.

Thanks for your help!