Things are always negotiable. It depends on how badly the scheduler needs a shop done. If the shop is in great demand and a lot of shoppers with 8+ shopper ratings apply, obviously the shop will be assigned to one of them. If the scheduler has no other options and a new shopper applies, the shop may be awarded to the new shopper.
Generally, you have to work your way up to the more popular shops. Most dining shops are harder to get and usually require a track record. I would say apply for some of the shops even though you do not have an 8 rating yet. Meanwhile, keep on the lookout for a retail shop or two you can take to build your rating. They shop hardware stores, cell phone providers, and miscellaneous third party shops. Some opportunities will probably come up even in a very small town.