If the shop has them, and if you are going to get an Alpha HS, then see if you can get the enermax adjustable. Otherwise any 80mm fan will do. If you are looking to keep things quiet though, make sure you get quiet fans. A local computer shop that I go to for work stuff has some generic fans that are very quiet and push a nice amount of air.
If you get an Alpha HS, make sure you have the fan set to suck off the HS and then that 80mm fan in the back for exhaust will do a great job at getting rid of the heat.
Good luck and let us know how it goes. Or give us the shop phone# and we'll give them a call! 😉