I have a really small HT room and as such we only have room for a couple "real" seats (we could do 3, maybe 4, movie theatre type seats but we opted for a 2 chair reclining love seat with center console). It's great for the wife and I, but for the occasions we have people over it's tough since there's just nowhere to put them. I have one cheap, small bean bag "video game" chair that I usually take and give the guest and my wife the good seats.
Anyways, I really wanted to get a couple of BIG foam filled bean bags but the $200+ price tag was just never reasonable for me. So, I decided last week to just make my own as I want to start up a monthly movie night with some friends of mine.
I picked up 7 yards of some microfiber/microsuede material at a local craft store for $40 (actually it's 14 yards at $80 as I'm doing 2 bags) and found a local upholstery/foam shop that I got 100 cubic feet of foam packing pieces for $80. They're little pyramid shaped polyurethane foam chunks with what looks like about 3 different sized pieces so they should fit together into am irregular but lump free blob.
My mother-in-law offered to sew the bags up if I cut/designed it, so I'm going a cylinder shape with 4ft circular ends and a 5ft wide tube connecting them. It appears to be the same shape Cozy Sacs uses. I'm figuring on (hoping since I ordered the foam already) about 50 cu. ft. per bag and seating one adult man, or a couple who want to be cozy with each other, or a couple small people/kids on each seat, so I can now probably seat as many as 7 people in my little theatre (2 on the recliners, 2 on each 5ft bag, and one in the old single seat beanbag which I am overstuffing with any left over foam material from the two new seats). The two main seats are the best, but the bean bag spots are a decent viewing distance and only about a 30degree angle so should be very tolerable.
Point is that if you're interested in saving some money by going for one of the knockoffs then you might look into making your own as I'm figuring about $80 per bag which is less than half the cheapest price I can find online (including shipping). I'm guessing that not including the planning an research time it'll be around 3 hours of work for each chair, so easily worth the $100+ savings, imo!