Be careful with GTC,  They roll over every month and is counted as a new listing. Thats with a store, so if you only get 40 listings and have used this lot of 100 GTC you may find you have no listings left, next month and paying.

That's why I always use the 30day with free listings, even when I had my store, as it was getting confusing when getting near the 200 listings.

Also if you have a store with 30 day you can go over your 200 with no listing fees.