Etsy shop funky3Dfaces will turn you into a Lego character, but it won't be cheap. 3D-printed heads small enough to plug onto a Lego body cost $30.08 on the shop, though the business is currently running a "buy two, get one" free promotion.
The business uses two photographs of a subject's head to create 3D-model, which it then prints onto a sandstone material with a 3D printer. According to the Etsy page, heads take roughly two weeks to ship, and they do not come with a Lego body. You'll need to supply that yourself.
If you're in the market for a custom torso, might I recommend Minifigs.me. The site has a lavish collection of LEGO formal wear.