The business of having a company in order to put real estate under it, is a little different to having a company that you plan to legally employee people under and do business here.
That said...
My advice would be to get a cedula if you plan to do retail business here.
If you don't have a cedula, you cannot legally work in your own business.
Will you get caught, maybe not, but why take the chance. The tax department are starting to get their act together here and more and more businesses are felling their hear here.
Talking of the tax man...
The part that takes the longest is an RNC (Registro Nacional de Contribuyentes) or tax number. It's pretty straight forward to create a company, but it takes a while to get a RNC or tax number. Lots of "legit" businesses now days will not do business with you unless your invoices etc have an RNC number.
Once you have the company formation out of the way, now the fun really begins. Then you get into the business of employing people, dealing with utilities, stock, security and the joys of dealing with the public
If your not a good Spanish speaker and very well versed in the DR, I personally think you will have a tough time owning and running a US$1 type store. Especially taking into account the areas these types of stores work best in.
Good luck and keep asking questions, we are here to help.