Hi Marcia,
I have a store because I sell a lot of different types of items. Also, I have quite a few items that don't have high turnover. Keeping them all in live auctions would be expensive in the long run. I also sell a lot of cheap items. I did the math and found that I would end up paying less in fees if they were listed through a store than through auctions.
It's really something that depends on what you sell, how much you sell, and how expensive it is.
There are some items which I always keep in auction format so they get the exposure. There are also some items which I always keep in my store because there is essentially no competition... when someone searches for them, they will show up.
I really like the perks of a store, too. The sales reports, the traffic reports, the email marketing, and Selling Manager are all beneficial to my business.
Can you still open a store with a free trial month? If so, give it a shot. It's easy to set up, and you will know at the end of the month if it is worth your money.
Hope that helps!
Roxi