The basket weave on the link is correct. I bought identical material from MarTrim in the UK to re-do my S2 seats recently. Incidentally the same basket weave is used on the S1 seats.
The "plain" vinyl is harder to match. It is quite distinctive because the grain size varies to make it look more like leather. I found a good match for the material in Australia, and it was used by Valiant (Chrysler). If you can, send a small sample to MarTrim and I am sure they will match it.
A Europa owner here in Melbourne bought Banks seat covers, and I wasn't impressed with the vinyl. It didn't come close to matching the original plain vinyl or basket weave. They were competitive on price though.
Cheers
Richard Mann
7004100119Q (sold last December after 29 years ownership)