I can't tell you price. Price is determined by what other magicians in your area are getting. My daughter's price was set by her then-SYM leader at the time before moving up into the adult group. He evaluated her show, the length of show, and determined her price. She has always done a 15 minute show (this summer she will be introducing her new 30 minute show) and she charged $75.00. Of course on top of that she has always been tipped, so she has never made less than $100.00 for a 15 minute show.
What you never want to do is undersell magicians in your area. It will not make you very well liked, nor will it get you any help in the future. Remember, you may need those friend in the future! What if you fall ill, and can't make a show? You have to have a backup partners to work with it and if undersell their shows you aren't going to get the help you need! What you never want to do is cancel a show at the last minute and not be able to offer your client a replacement magician.
As to walk around magic my daughter doesn't do it. Oh, she has a few pocket tricks she does to the adults, and some for the kids, at the parties but she bills herself as a stage performer/parlor magician and does not do walkaround. She sticks to what she likes best and works on that to be her personal best.
As to a vest, again-- couldn't tell you since it would all depend on the shops in your area. Since you are male, I would suggest the Mens Warehouse. My daughter just bought hers at the local mall at Macys.
i know a 9 or 10 year old magician in my area that has been hired before!!!!!
Getting hired is the easy part---- getting re-hired is where it gets tricky. Anyone can get their first chance at something, its waiting for the phone to ring to get the callback that lets you know whether or not you really did your job.
Edit: You may not NEED a vest, my daughter does as part of her act, but that doesn't mean your act will require one.