I buy the Perlite at the Grow Biz, I’m sure they sell it at online stores (make sure you buy plain unfertilized) I built a indoor garden with PVC pipe, Panda film and diamond Mylar. I got the PVC pipe and fittings at Home Depot, Panda film from the Grow Biz and the diamond Mylar from Amazon. It works, but I’ve had some trouble keeping it warm and humid. There are light leaks but I’m growing auto flowers right now so that isn’t a problem. It can be made light proof for photo period plants.
Before I made the PVC garden thingy I was growing in a bookshelf (without the shelves), the plants were outgrowing it so I had to make something bigger.
Honestly though I almost spent the same amount as a grow tent. They sell reasonably priced tents on Amazon if you have Amazon Prime you can find one and get free shipping