Better yet, why not let the user define the amount he wants to trade by chatting it?
1: onActivate > Client > CenterPrint > <color:ffffff>Please chat the amount you wish to trade.<br>Click me again once you have.
2: onActivate > Self > VCE_ifValue > <var:cl:wood> >= <var:cl:lastmsg> > 3 7
3: onVariableTrue > Client > VCE_modVariable > Wood > Subtract > <var:cl:lastmsg>
4: onVariableTrue > Client > VCE_modVariable > Cash > Add > <var:cl:lastmsg>
5: onVariableTrue > Client > ChatMessage > <color:009900>Cash: <color:ffffff><var:cl:cash> [+<var:cl:lastmsg>]
6: onVariableTrue > Client > ChatMessage > <color:663300>Wood: <color:ffffff><var:cl:wood> [-<var:cl:lastmsg>]
7: onVariableFalse > Client > ChatMessage > <color:ff0000>Please specify a number less than <var:cl:wood>.