Intex Essential Wave Inflatable Mattress (Full Size)
Includes electric pump (fills very quickly)
Very good quality! - bought 1 month ago, used ONLY by me, while in a temporary apartment.
Can adjust for firmer or softer, by filling more or less.
Paid $39.96, asking $25 OBO
(http://www.walmart.com/ip/Intex-Essential-Wave-Airbed-Kit-Multiple-Sizes/23772699)

Will throw in brand new (unopened) 5-zone mattress topper (Twin-XL) for $5
Great quality - I used one like this in a different size in a previous apartment to cover a too-firm mattress. It was very comfortable! Bought 1 month ago but never opened, since my current air mattress didn't need it.
Paid $9.94, asking $5
(http://www.walmart.com/ip/Mainstays-1.25-Convoluted-Foam-Topper-Twin/10055840)

Pickup from Mountain View, if needed I can probably deliver to campus for $10 extra