Down to my last Walmart bags

[Jetstar]

I'm really not looking forward to next year as this will be the last year I'll have enough 7 gallon blue Walmart bags, since they stopped selling those .50 reusable shopping bags that made a fantastic grow bag. So anyone know of a low cost grow bag? I really don't want to go bigger than 7 or smaller than 3 gallon since the area I have to grow in just doesn't have a lot of room, this pic shows the limited room I have. Any ideas on grow bags would be welcome. Yes for those wondering I do reuse the bags but 2yrs of use is about all the life I can get out of the Walmart bags. Thanks for any ideas on grow bags.