Unless you really luck out, the mattresses are going to be at least a few years old. Mattresses get rotated around, so there's always the slim chance you'll get a new one, but I wouldn't count on it. Depending how firm/soft you like your bed, it's worth buying an egg crate or memory foam topper. FWIW, I wouldn't buy it from the direct mailer. Egg crate is around $10 at Bed Bath and Beyond, memory foam is around $25. Watch the back to school sales and use coupons for the best deal.

Don't forget to get Twin XL bedding!