I used to own an e3, and as I recall it used the same style of carpet as an e9. Sort of brown + "color", where "color" can mean tan, blue, red, ... See first photo below.
If that's the case, then it's going to be tough to find and EXACT match. The stuff is just NLA. My upholsterer found a generic blue carpet whose weave is close,, but it lacks that two color pattern - see the second picture below.
Not sure how the heel pad will last given its just vinyl on those velour carpets. I think you get what you pay for, try GAHH. They did square weave for my early 02 and have German loop for our e3 and e9.
For my Si I went with the "German import multi-loop carpet" from WU in Hazel (9711) which gave me a near perfect match. In speaking with them, it became clear the pre-cut kit for the Bavaria wouldn't fit the Si perfectly since the latter has heat ducts under the seat and different front seat mounting than the Bav so I bought the raw material and had an interiors guy cut it, apply the edge binding and install it. Don't have the car with me yet so I can't provide you with pictures...
I thought World Upholstery and GAHH were somehow related? I have always been happy with World Upholstery products, have purchased for E9's and 2002's. They have stock patterns for E3's and are one of the best bets for original material products. If I ever re-do another E3 I'll look to them for carpets based on my past experience with them.
Try looking up "Esty" from the 2002faq group. She's going to be doing a set of carpets for my 2000 Touring and comes very highly-recommended.
That eBay seller also lists loop carpet sets for the E3 (not just velour/cut pile), check their "other items"