I think the OP is referring to something the C4C can use when he sleeps on the floor so he or she doesn't mess up the bed prior to an AMI!
We bought our DD a comfy blanket from Walmart that she rolled up in on the floor and she seemed to do just fine with it. I've heard of other parents buying a sleeping bag plus a mattress topper...seems like alot, but hey, sleep is important.
Except for days when the upperclassmen are your only alarm clock or you have a full-on SAMI at a ridiculously early hour, I think it's unnecessary to sleep on the floor. Yes, I did it a few times, but I'm lazy and don't mind sleeping on hard surfaces. About 98% of the time you can either fold the comforter and tighten the already made SAMI bed (works for all but the most precise inspections) or make it on Saturday morning.
Now, if you like to camp, having a good sleeping bag is important, and you might use it more for SAMIs (as you already have it), but I don't think it's a critical item.
My C4C did the same - slept on top of his made bed and didn't have to worry about Sami's at all. He requested it and was glad to have it.Our son had a great one from LL Bean. Got it from my boss as a high school graduation gift (it was the one thing on his list). Used it a lot his C4C year (he was in an unremodeled room where ice froze on the INSIDE of the window). Also, used it extensively when they took his Jeep up in the mountains to camp and shoot skeet.