Here is what I found. The first link is the only place I found them in stock & they want $98 for them. I think you could make one by looking at the picture. Walmart, Walgreen's & CVS have apparently had them in their stores for a lot cheaper but no one show them in stock. Hope this helps you.

https://www.1800wheelchair.com/produ...r-wheel-pouch/

https://www.cvs.com/shop/wheelchair-...prodid-2350510

Edited: Just found these in stock for more reasonable price:

https://www.4mdmedical.com/index.php...caArFEEALw_wcB

https://www.healthproductsforyou.com...eel-pouch.html

Thinking that this could be made from weatherproof fabric or could be sprayed with Scotchguard after it's made in case of rainy days.