If you say, wanted a gun for 50 points...
onActivate > Self > VCE_ifValue [<var:client:score> ] >= [50] [you can leave this blank]
onVariableTrue > Player > additem > [Gun]
onVariableTrue > Client > ChatMessage [You bought a gun!]
onVariableTrue > Client > IncScore [-50]
onVariableTrue > Client > ChatMessage [You now have <var:client:score>.] (optional)
onVariableTrue > Client > playSound > Beep_TryAgain.wav (optional)
onVariableFalse > Client > ChatMessage [You need 50 points to buy a gun.]
onVariableFalse > Self > playSound > Beep_Denied.wav (optional)
onVariableFalse > Client > ChatMessage [You have <var:client:score>] (optional)