what you need:
Repeater X1
Item granter X1
Vending Machine X1
Wire X1
Summary
First make the repeater stop when reciving on chanel and make the interval 1 second.
Wire the repeater to the item granter and make when repeater runs, grant item.
Change item granter to cash, amount of item 1.
Then you want to wire the vending machine to the repeater and make it when item purchased start repeater.