Does your community offer it? The school district recommended I call the sheriff and talk about getting one for DS.
Would you get one for your child? DS has Autism and wonders. Better safe than sorry. The woman at the parent resource center was telling me last year an autistic kid my son's age wondered away and was lost for six nights.
On one end of our road there is a pond, the other end is woods with a creek, woods behind our house, and woods with a steep drop ( 20-40ft ) with a creek at the bottom behind our neighbors house. With all that I constantly worry and have to keep all the windows and doors locked at all times.
http://www.princegeorgeva.org/index.aspx?page=578