Hi
It's much easier to stick with the best 3 prices because all the variables are available in MFP and you can just write conditions to check the amounts offered as Tim suggests.
If you want to check amounts offered outside of best 3 prices it needs a lot of conditions to check each price backwards:
LAY at r_ticks(back_price, -3)
selections trigger expression b_offered_r_ticks(back_price, -3) is greater than 100
OR
LAY at r_ticks(back_price, -4)
selections trigger expression b_offered_r_ticks(back_price, -4) is greater than 100
etc..
Attached is a trigger which will scan the prices downwards from best back price looking for a specified amount.
When it finds the amount it will write the price to a user variable "tonup"
The trigger will cycle though the prices downwards to a maximum number of ticks you can set
in the constant and then it will start scanning again from back price
There is also a constant for the amount to look for.
Add your lay trigger below this and use tonup for the price.
For this to work you need to turn on Download All Price Offers in the settings.
Please test in test mode.