I currently have 5 of them, the 4 pictured above, and this one:
Honestly, they aren't really THAT expensive. I only have around $500 invested in the hobby. I got a couple for free(actually, I traded labor for them), and the others, I just had good deals drop into my lap. I don't really have a lot of money to put into them, so I've done all the needed repairs on them myself.
If you think he'd be interested in getting some, feel free to shoot me a PM. I'm on a collectors website, and they are generally happy to help out locals. Plus I can offer advice on where to find them, and what general prices to look for. Mainly, it's all about condition. You can find non-working cabinets cheap, and fix them yourself(which isn't as difficult as it sounds), or decent working ones for mid-range prices... all the way up to "fully restored" for premium prices.
If there's a bad side, it's that some people just don't realize the ACTUAL value of them. Some people think, "Well, it's old as shit, therefor it's worth a lot of money." Ummm..... no. Not really. There are exceptions to that, but they are few and far between.
The only downside to them, is that they're heavy as shit. Atari cabinets are easily in the 325-350lb range. I rather lucked out with Dig Dug, since it's a cocktail table. 100 less pounds to haul around.