looking for a Grid EA with user defined scale

Hi,
I'm looking for a simple grid EA that buys when market drops and sells when market rallies, so only limit orders. User must be able to choose the scale at which the EA buys and sells.

for example:
market price is 1.2000
Say that user wants to buy or sell every 30 pips. Now when market price drops to 1.1970 the EA buys X amount (user defined), if market drops further to 1.1940 the EA buys again SAME amount (no martingale). If market retraces back to 1.1970 market sells same amount that it bought from 1.1940. If market retraces back to 1.2000 it sells the initial position which was bought at 1.1970.
I know similar EA's have been around but i want the very very core of this EA. No filters. just buy when market drops and sell when prices rise. User must be able to define the quantity and the pip amount it wants to buy or sell. Maybe any of you have this EA already ?

Very special wish, there are many grid EA s on FF, you need to modify one of them. But dont forget, in this case, all opened position have unlimited risk and gridsizedprofit, which make all of the simple grid systems looser.