After recovering from the sticker shock, folks will ask me for a less expensive way to wall mount flat screens in their homes, churches, etc. I have seen the wall mounting brackets for these flat screen wall mount televisions and/or monitors sell from $80.00 to over $400.00. I agree that it is quite an outrageous price for what they are.
There is an age-old, inexpensive, method for mounting cabinets and other heavy items that also works well for wall mounting flat screens. It is called a "French Cleat" This time-honored French cleat is a system that uses two beveled lengths of wood. The top block is screwed to the hanging object. The other half is attached to the wall. When you place the top half of the cleat over the bottom half, the item is locked firmly in position. To make the cleat, one simply cuts two pieces of wood at an identical angle on a table saw or, lacking that, using a circular saw.
(Simply type "French Cleat" into a web search if you are not sure how to make one.) (Scrap hard-wood makes a good cleat)
If one does not need to swivel, pull out, or tilt their flat screen, this mounting method will cost you next to nothing. I have also noted that some of those expensive mounting brackets, stick out quite far from the wall. This mounting method will pull the flat screen closer to the wall, hiding unsightly cable connections.
I hope this is helpful and saves you some money