The APs are probably lower quality too.
The Asus RT-N16 has a setting that will turn it into just an access point, and all you have to do is connect it to the router. It will look something like below.
Edimax --> RT-N16 --> switch
You can either get rid of the switches or hang them off of the N16, and to get wireless roaming, setup each N16 to have the same SSID and password.
If you want to get really crazy, you can flash it with TomatoUSB or OpenWRT, and use it as a wireless bridge and such.