A replacement bag for an air mattress may be purchased wherever bedding accessories are sold, for example Anna's Linens. These bags might also be bought at Walmart, Target, K Mart and Sears.
Return it to the dealer for replacement.
I haven't tried this myself yet, but I recently saw a post in which a gentleman described how he taped a small/cheap vacuum bag (the kind with the vacuum cleaner valve) inside a mattress bag that he purchased to fit his mattress. He cut a hole in the mattress bag for the valve to poke through, put his mattress in the bag contraption, taped the mattress bag shut (making sure that the holes that he cut for the valve are tightly sealed), sucked the air out of the entire package using the valve. His 12" memory foam mattress looked like it was reduced to about 2 or 3 inches thick. He then rolled the entire deflated mattress up & tapped up the roll to keep it from unrolling. A few people commented that this solutionw worked for them as well. Just search on "memory foam mattress vacuum bag" and you'll see the post with pictures.
You can pretty much purchase a twin bed mattress protector anywhere. Target, Walmart, and Bed bath and beyond are some great places to check first. Maybe even check the place where you got the bed.
There are several places where one can purchase an air bag. These retailers include Auto Anything, Xtreme Diesel Performance, SD Truck Springs, Street Side Auto, and CARiD.
by placing a pillow inside a toy wheel
The self-inflating ones are inflated by opening a valve which leads to an air bag that has a piece of foam inside it. With the open valve, the foam is able to suck air into itself so it can go back to its normal size. Air is also sucked into the other areas of the air bag. When the valve is close and you lay on the mattress, the air tries to escape the foam but it can't. This makes it just like an air mattress or sleeping on foam. To deflate it you open the valve and start rolling it up from the other end. This squashes the foam and all the air can escape through the open valve.
You should stick with the air mattress because if you wet the sleeping bag it will take a lot to clean it. You should buy an individual plastic cover for the air mattress so if you have an accident you can just clean it off with no fuss or more mess.
You can get a Firestone air bag suspension kit online from the Auto Anything website. Alternatively, you can purchase these kits online from websites such as eBay and Craigslist.
Just the air bag
You DoNOT Repair!!!! SERVICE IS MADE BY REPLACEMENT ONLY. DO NOT ATTEMPT REPAIR OF: CRASH SENSORS, AIR BAG SLIDING CONTACT, AIR BAG DIAGNOSTIC MONITOR, AIR BAG MODULES IF A PART IS REPLACED AND THE NEW PART DOES NOT CORRECT THE CONDITION, INSTALL THE ORIGINAL PART AND PERFORM THE DIAGNOSTIC PROCEDURE AGAIN. WARNING: AIR BAG MODULES WITH DISCOLORED OR DAMAGED COVER DEPLOYMENT DOORS MUST BE REPLACED, NOT REPAINTED. NEVER PROBE THE CONNECTORS ON THE AIR BAGS. DOING SO MAY RESULT IN AIR BAG DEPLOYMENT WHICH COULD RESULT IN PERSONAL INJURY. ALL COMPONENT REPLACEMENTS AND WIRING BEING SERVICED MUST BE MADE WITH THE POSITIVE BATTERY CABLE DISCONNECTED FOR A MINIMUM OF ONE MINUTE BEFORE SERVICE OR REPLACEMENT IS ATTEMPTED. THE INSTRUCTION "DISCONNECT" ALWAYS REFERS TO A CONNECTOR. NEVER DETACH A COMPONENT FROM THE VEHICLE WHEN INSTRUCTED TO "DISCONNECT."
There are many places where one can purchase a drum bag. One can purchase a drum bag at popular on the web sources such as Musicians Friend and Amazon.
Once an air bag has been deployed, there is no fixing it. Replacement is necessary and the cost would depend on the year, make and model vehicle.