Every time I go to order one they’re out of stock, probably just timing, but is there a similar alternative from anyone else available for about the same price?

Nothing else tapered as far as I know. If it’s to go inside a harness, etc then pretty much any dry bag of the appropriate size will work fine.

A standard Exped dry bag will work in a typical seat harness like the Wildcat Tiger, the main problem is pre-packing it so that it fits snugly in to the harness.

There are other tapered bags that are made for canoeing but they are much bigger, typically 25 – 45 litres.

I’ve already managed to lash regular shape Airlock xtra bags under my seat, it does work but I decided I wanted to try the Airlock taper because well… it’s tapered, and about the right capacity for my needs, is designed so you don’t need a harness and hopefully won’t catch my thighs as much…

On top of that I don’t want to spend the money for a fancy harness, they’re a great idea but I wouldn’t get the use TBH, it’s just for occasional jaunt, and the cost of a koala/tiger + airlock Taper Vs the plain old Airlock taper on it’s own put’s them more in “serious bike packer” territory than mine…