Server racks are expensive when new. APC makes a really good server rack. If you shop for one, you want to make sure that it is a four poster, and not a two post data rack. The data rack are okay for switches, but not for servers. Also, a good tip is that since server racks are so heavy, they are hard to get rid of. That means that local companies that want to get rid of racks will give them away for cheap (or free) if you will take them. Craigslist might be a good source for that. Or maybe ebay, but search for people local to where you are.
If you buy a new rack, consider how you will do power. Often you want (in U.S.) 220 or 208v from the wall to a UPS at the base of the rack. Then you have a PDU (power distribution unit) that runs along one, or both sides to give places to plug your servers in. PDU's can provide 120V or 220V. my apologies if you are nt in the U.S. and have different power requirements. The same pricipal applies though. With a small operation, one UPS running from one dedicated circuit (isolated ground) on the wall can work. For a larger operation, two racks, with a UPS in each rack, and then each rack having two PDU's along the sides, with one PDU on one UPS, and one PDU on the other UPS (crossing between racks) and then servers with fault tolerant power supplies one plugged into one PDU (to one UPS -- to one circuit) and the other power supply into the other PDU (and other UPS -- other circuit).
Another factor, other than power for your racks, it so consider heat flow and HVAC. Rack mounted servers are designed for fresh cold air coming in the front, air flow through the servers, and exhaust of hot rising air out the back. Making sure that your ceiling tiles have a return air, or ventilation tile behind the rack(s) is important.
