How do I mount a flat screen TV on the wall? Best Buy, where I bought it says I have to buy special brachets which cost $250! That is crazy. Also, how do I clean up all the wiring so it doesn't look messy?

You really should buy the bracket, you don't want to buy some no name brand bracket and have the TV fall, I'm sure this wouldn't be covered under a warranty. To hide the wires, run them behind the drywall.