I haven't used shorttime many times, but I know there is on at the end of Soi Easy, I think they charge 500 Baht. I use Touch Villa...right down Soi from C&N
Hotel. 350 for fan room and 450 for AC.
theres one on rat-u-thit across the road from post office. 300 baht. you tend to learn this stuff when you pay 15000baht for a room and have everyone who works there rat you out and gte in your business! no, im not bitter