Many sporting and hunting outlet stores, such as Dick's, carry both wooden and metal slingshots as well as ammunition. Online retail sites, such as eBay, Craigslist and Amazon, are also places to buy slingshots.
Dick's Sporting Goods and other sporting/hunting stores have a wide selection of slingshots with prices ranging from just a few dollars to about 50 dollars. eBay and other online sites also have many low-priced, new slingshots, as well as used ones for even cheaper.
Both sporting stores and online marketplaces sell ammunition, too, including both metal and rubber pellets. Many retailers will also sell replacement parts for slingshots, mainly the rubber band, for just a few dollars.