My experiences with the Pinball Exchange (now located in Hamilton) are mixed. I did buy my High Speed (for retail minus a trade in value for my Wizard!) there and it has been issue free for years.
I did however request a price on an Alien Poker (as Dallas has a few I saw in the storage area) and didn't receive a reply on my numerous inquiries. Also asked how much extra the 'multiball mod' would be if they installed it. They claimed they didn't do mods but now I see they will mod lighting to LED for a extra fee.
Also of note, the retail prices listed have jumped since last year. I guess inflation is catching up.
Also they have a massive amount of disassembled machines in the storage area but wouldn't part with one to my tech buddy for a project machine. Either they fix it up and sell it (for retail) or it's not going anywhere.
Just my experiences.

Yeah, it would be great to hear some first hand accounts. I shared my TOPEC experience. I did once have a few e-mail exchanges with him as he claimed to have an Alien Poker, but he was way up in the clouds on price.