Be careful with the street guys. I made the mistake of having one work on a watch in Santo Domingo and he was a butcher. I knew I had made a mistake the second he started working on it, and I walked away thinking "never again".
If the watch is inexpensive and you don't care that much for it, then that's a different story. If you need it resized and you care anything at all about it, take it to a reputable shop.