It really all depends on what you are looking for and what you consider cheap. Look below and check out the sponsor forums. There you will find quality vendors. Some are expensive and some are less expensive. Most have great service. If you are looking for truly cheap then look at other hobbiests that are selling.
Locally only. Try to trade as much as possible. Never ordered online as I'm not home during the day. I have been contemplating ordering from a couple of vendors here because of good looking corals for decent pricing even with shipping. May try and use a vacation day when expected to be delivered.