I am dreaming of a Tyvek-like pannier for commuting because I want a pannier that is
1. fixed to the bike (mine get grimy--ick) s.t. trying to steal them would effectively destroy them
2. very lightweight s.t. I won't care that it's always on the bike
4. strong enough to hold my lightweight tote bag of work clothes, lunch, etc (which won't get wet or grimy)
Does such a thing exist?
Would I be the only one to buy them?
I've got some panniers from Performance, and they're waterproof and strong, but they're too heavy to consider fixing to the rack.
To my knowledge such a thing does not exist, and you'd have to make it yourself.
I've never seen a pannier that was all that heavy... the Performance pannier you mention is probably just as light as what you want to put in it.
Tyvek isn't very durable. If you have anything pokey (like the corner of a book) it will put a hole in the material after a short while.
Another choice for a fixed yet durable pannier is a military surplus bag. It can be treated so that it's water resistant (if the bag isn't already), and it's possible to get a very durable bag for a great price.