Changeable digital signs are the most effective means of advertising out there with costs per CPM of approx $.75 versus $8 - $12 for TV, Radio and newspaper. Before buying an LED sign, you need to know the local ordinances and code pertaining to their usage.
Most jurisdictions have limitations on LED signs regarding size, frequency of change, brightness, etc. The best bet is to hire a sign company who has extensive experience with LED signs in order to make the transaction a smooth one - otherwise, you could be paying $1,000s for something you can't use.
Regulations to keep in mind include: Collier County - Naples - no LED signs allowed. Sarasota County - no LED signs allowed. Manatee County, FL LED signs allowed with some limitations. City of Sarasota, FL - LED signs allowed with some limitations. City of Tampa and Hillsborough County allow LED signs with some limitations as do Pinellas County, Largo and the City of St. Pete.
The City of Orlando does not allow LED message signs although Orange County does. Osceola County does allow LED signs.
Polk County, Bartow, Lakeland and the surrounding areas do allow outdoor digital led signs.
The City of Sarasota allows outdoor digital signs but the message can change only once every 24 hours.
Some jurisdictions allow a portion of the overall signage to be LED sign. For instance, Manatee County allows 65% of the total signage to be an LED message center.
We recently installed an LED sign for Action Air in Tampa, FL (see pic) and there we were allowed 50 sf of signage - and it could all be LED.

Please call 941-755-5686 for more detailed information on what is allowed or not allowed in your jurisdiction.