In message , Broadback
writes
Any suggestions on which fabrics are good and which not, also cheapest
source?

What sort of weeds are you intending to suppress?

Any of the black woven fabrics that will not tear easily with 4" of
mulch on top will discourage all but the most persistent of thistles.

A few plants and weeds can punch through anything up to and including
tarmac but they are quite rare.

Regards,
--
Martin Brown