I need some recommendations for websites that are reputable. I've been looking at FCP euro and they seem to have a good selection and parts I need. Any other reputable websites would be good too if FCP isn't what I thought it was.

 

ECS tuning is pretty popular, I have bought a few items through them.
https://www.ecstuning.com/

 

Besides ECS Tuning and FCP Euro, there are several additional sites for OEM parts at a discount. Some of the supplies I have used are: www.autohauseaz.com, www.audi.oempartsonline.com, and www.usaaudiparts.com. I usually check for their part price with the shipping cost because some of the shipping costs are excessive.

 

I've had 4 C6 Avants, bought used from Bought '06 at 180K and ran to 220K, '07 109 to 180 and sold it to my mechanic who ran it to 220 before needing larger car, was still on the road last I heard. '08 at 129K and my daughter is still driving it at 267K, down now for steering rack. I'm driving '10 I bought w/ 110K and now at 217K.
IHaving a great mechanic who is a friend I do the parts sourcing. The absolute best non AUDI source is Northside Import Parts BUT it's dealer only & you have to set up an account! While Rock Auto offers many options, some really cheap there personnel don't know AUDI'S AND ARE OFTEN INCREDIBLY INEPT. I got a very nice radiator hose that had the part label stapled to it, piercing the hose! Another time I got a part that had plastic mounting flanges broken of due to rattling around unpadded in original box which was surronded by bubble wrap. Box was fine but part was useless.

FCP Euro is pretty good and you can't beat their refund policy! I buy Motul oil and filters from them and ship the old stuff back Truly amazing! BUT their stock of original & some OEM AUDI stuff isn't very deep and the wait times can be awhile.

For the most reliable European parts source I've found Germanautoparts.com to be an amazing operation. They were a brick & mortar store N of Albany, but eventually closed their public operation! I believe they have several warehouse of their own & source stuff they don't have from Northside and perhaps other sources. Mark, who you'll get on the phone knows his business extremely well. When ordering the rack & hose for my daughter's car late last Friday I gave him my VIN & the part numbers for hoses & tie rod ends my mechanic had given me. He priced out the order & emailed me shortly asking if I was sure the numbers were. We'd mistakenly given him a number for another hose & noit return hose! He emailed a picture of the parts diagram with the parts we'd oredered circled and the correct hose we needed circled in another color!
SO, for consumables, oil/filters/pads/disks/wiper blades I use FCP and et the next one for cost of return shipping & whatever the price has risen to since you purchased the previous. YMMV
And a good source for used parts is Lifetime AUDI in NC. Ordered steering rack Fri $115 shipped and here Wed.