With most gas stations and convience stores around here, the owners of the store do not own the movies that are available for rent. There are lots of options with renting videos in small shops.
There are companies out there that will give you a certain amount of movies, and want a % of the profits, which is usually a high number. In Canada, Rogers Video wanted 60% of the profits, had to sticker all the movies with Rogers stickers, but they were going to give a Point Of Sale System (Rapid Rental) for free. They also order in your movies for you, you just sit there and rent them. Im not sure if the offer is still available with Rogers, since that was in 2002. It was called Rogers Shows To Go or something like that.
If you wanted to keep it small, you could just go with New Releases only, and avoid the catalogue, or cheap titles. This would work well if you are short of room.
Bringing in your own titles through a distributor is a way to get all the return on your rentals, without having to share your profits. The Canadian Distribution Companies that u can contact for catalogue and sales information are;
VIDEO ONE; 1-800-665-1330
HIP INTERACTIVE; 1-866-525-8746
Be sure to give both of them a call, to see what they both have to offer, and tell that that u r interested in the other company for a bigger percentage discount of the Sugguested Retail Price (SRP).
Be sure to ask all your questions now too, so u can get into the business with a little know how. Im sure there will be lots of posts following this one, be sure to get James' opinions too.

Good luck!