Be careful. All slot machines are not the "Vegas" one arm bandits. There are the Japanese "Skill Stop" machines where you press a button to stop each reel, and there are the "real" electronic or electro-mechanical slots that were in real casinos.
The "real" machines are regulated in almost every state and usually have to be at least 25 years old in order for you to possess them. These usually sell for $700 and up and are typically old Bally EM machines from the 70's. I have restored several of these and currently have a 4-reel Bally Continental in my basement under restoration.
The Japanese skill stop machines are neat. They have elaborate themes, play music, and usually take tokens. You can buy them on eBay for around $300 and up.
If this place is selling real slots make sure they are legal to have in your state. Also, parts are available, at least for the Bally's, from several vendors.
Have fun.