The only EA I am familiar with that sells off at prescribed Fib levels is the 4H-Vegas system that has been posted on lightpatch.com/forex. You may want to check it out. It uses a MA tunnel approach. I am sure that other Fib sell-off EA's exist though.

Regarding creating an EA, a suggestion. Define all of the indicators and trading rules to the point that you can build a flow chart/decision tree with verification through notes made on all of your manual trades. If you have complex decision rules, it is much better to define as many as possible up front rather than add them piecemeal. Some adjustments will probably be needed later anyway such as timefilters, etc.. This way, it will be much easier for someone to program your EA.