This is going to depend on where you live. There are many reputable tattooists who will gladly take a photograph and produce a high quality tatto image for you. There is a federation of british tattoists, the details of which I do not have to hand at present. You can obtain the details from any tattoo magazine available from large newsagents such as WH Smith (Skin Deep etc).
Some artists to beutifull portrait work... some are really bad. Best idea is visit a load of shops (http://www.yell.com
for a list) and watch. The artist won't mind. There's nothing worse than someone jumping into tattoo's they won't love