I recently sold my 99 A6 Avant and have a bunch of the accessories FS that I collected over the years. What I have listed below is just for the parts with no shipping included. You can pick up local in the Spokane area or I can ship to you if you want. Only part number I couldn't find was the carpeted cargo mat which is for when you have the 3rd row jumper seats in.
Part # Description Price Sold? 4A9 861 869 Cargo net $15 4B9 861 691 A 5TE Cargo net cover $50 4B9 071 151 666 Roof rack crossbars $130 SOLD ZAW 179 002A CLY All-weather floormats $30 ZAW 452 800 BLK Rubberized cargo mat $25 SOLD Couldn't find the part # Carpeted cargo mat for 3rd row seat $25