Keep the issue of "grandfathering" in mind when comparing existing businesses in an area to one you might start nearby. As a new business, you may need to obtain licenses and permits (and take additional regulatory compliance steps) that an existing business may not. "Grandfathering" is something you need to watch out for ESPECIALLY if you are considering buying an existing business from an owner who has been in the same location for a significant period of time.

The key thing to remember with "grandfathering" is that, once a business changes hands (i.e. it is bought and sold) the new owner will most likely be required to come into full compliance with all local regulations, including any from which the prior owner was exempted, and so may need to obtain certain licenses and permits that were not required of the previous owner. This can be an expensive prospect for a new business owner if, for example, obtaining these permits requires major building renovations to meet existing building access requirements -- such as widening stairwells or even installing elevators. In such a situation, before you buy the business it is extremely important that you contact your local government (at the city, county, or town level) to find out what licenses and permits would need to be obtained.