This is what retrocheck is for.
No. I'd advise against retrocheck just because it does not follow the same format as the rest of VCE.
OP:
[0] [x] [0] [OnActivate] [Self] [VCE_IfValue] [<var:cl:score>] [>=] [5] [1 4]
[1] [x] [0] [OnVariableTrue] [Player] [AddItem] [Sword]
[2] [x] [0] [OnVariableTrue] [Client] [IncScore] [-5]
[3] [x] [0] [OnVariableTrue] [Client] [Centerprint] [You bought a sword]
[4] [x] [0] [OnVariableFalse] [Client] [Centerprint] [You don't have enough points to buy a sword]
This is a very basic, but good place to start with a store. This checks that you have enough points (5) that corresponds to the price of the requested item (sword). If you have the required points (5) or more than that, then you get the sword, and the points (5) are subtracted from your score. The item (sword) is then added to your inventory. From this basic store system, you can expand to include checks that: can ensure you have an available slot for the sword; if you have bought it before, then the item is just added to your inventory, without a loss of points; etc.