I'm guessing it's 25+ years (legal in all but a few prudish states), and has no chips or circuit boards - so it should be relatively easy to fix, if you are mechanically inclined. Parts for older Aristocrats are harder to find than for Bally (what I collect), because Aristocrat is an Australian company, and there doesn't appear to be much of an Aristocrat collecting community to access for help or parts.

If the machine is older and has electronic innards, I'd avoid it, as it will be very difficult to diagnose, and nearly impossible to find replacement boards. If the machine is modern, you may be able to find a modern slot tech who can help you, and you may be able to find parts...

Unless you live in Australia, or have a friend that's a slot tech, I'd recommend getting a Bally. There are many different models to choose from, and many boring "plain jane" models to avoid. I've linked an Ebay auction of the Bally book that got me addicted to collecting Ballys - it features sales flyers describing the play and features of all their best Electro Mechanicals. Although it doesn't list price values, it makes it much easier to determine on your own how rare a certain type of machine is. I wholeheartedly recommend this book, edited by the grandson of the inventer of the first slot machine!

The trick to buying a slot is to find a good one within driving distance; buying one long-distance can cost $300-400 to ship! Overseas shipping can go over $1,000!!! So, if there is a desirable machine on EBAY within driving distance, you have a big advantage over the competition (who would have to pay shipping). Good working Ballys generally go from anywhere from $200-$1500 (higher for the rare, desirable machines). Many concluded auctions don't get completed, because buyers freak when they hear the final shipping cost. I've picked up some good local machines that appeared to sell on EBAY, but the buyer(s) wouldn't come through. So, when it's a good machine that has bidding over what I want to pay - I don't bid, and contact the seller to let them know I'm interested if the buyer bails...

Remember; many sellers only have one machine, are bored to death of it, and think of it as a big paperweight that they just want to get rid of... Once a few buyers bail, and the illusion of a big EBAY payoff vanishes, THEN you can frequently get a good deal.