If you're in need of a sleeve that feels a bit more like you, than the plain boring ones, Designer Sleeves has just about every style you could possibly want. They have 47 different options and not at a bad price either.
At first I was unimpressed since some of them look a bit like the generic backgrounds offered by Windows, but I soon found ones that I couldn't live without. They have everything from the excessively girly, to the slightly generic and even a slightly more badass Bio Hazard sleeve.
The sleeves are made out of neoprene rubber and come in three different sizes. The 13” is being sold for $34.95, 14.1” for $36.95 and finally the 15.4” sleeve for $38.95.