Buying new range balls will be easy. There are several distributors and brands to choose from. Titleist makes their driving range balls with Pro V1, Pro V1x, NXT, HP Tour or DT Solo, and will range from $6 to $20 a dozen with a minimum order requirement. Callaway offers range models of their Warbird, HX Red or Blue and HX Tour with a prices spanning from $8 to $20 a dozen. Top Flite has their Tour Straight, XL or Tour Ace plus other models. These come with some of the best prices--from $5 to $10 a dozen, but they also require a minimum order.
Many driving ranges start out with used balls. Theses are the ones found at the bottom of the ponds on the course. Most courses have divers retrieve the lost balls from the pond and lake bottoms surrounding the fairways. Many of the divers will keep balls or split them with the golf course. Some companies will send divers to your course to retrieve the golf balls and pay you per ball.
These balls find end up at businesses that recondition them and put a driving range stripe on them. You can find these for around 25 cents a ball or $3 a dozen. Most companies that sell these will require you to purchase at least 50 dozen to make it worth their time.
You can get custom-made driving range balls with the name of your business or golf course on them, along with the driving range stripe. These are going to cost you a little more than the others and a one time setup fee for the printing.
The other type of golf ball you can get is the limited-distance ball. These don't travel as far as regulation balls (from 50 percent to 80 percent) and work better for ranges with limited space. Just remember to tell your patrons about these balls so they can calculate the total distance they hit a normal golf ball.