You pay a listing for for that item number once. If that same item number continues to list for X number of weeks, your still only charged the fee for the invidual item number.
If there is a new number, you would be charged again in 30 days. That is only if there is a new item number attached to that listing though, which I believe eBay does do for 30 day storefront listings. (im not 100% on that though, as I do not have a test item available to confirm this behavior)
Under the Pay as you Go plan, you pay 10 cents to list any auction for the first 50 in your billing cycle and 5 cents an item for items over 50 in that same billing cycle.
I can confirm that Vendio will only charge you to list an item number once. As soon as the item has a new number, you are charged to list the item again.
