I got my GSP at Costco for $79. Last time I was there they still had a giant stack at my local warehouse. A friend asked me if they were any good, and after looking online, I had to grab one. Before I even opened the box I grabbed a microSD card, downloaded a bunch of ROMs from the Internet Archive, and was ready to go. This YouTube will tell you everything you need to know!
The joysticks are not the greatest, but the unit sports compatibility with many of the most popular controllers today. I use an Xbox One S plugged in via a USB to USB-C adaptor when I need more comfort and better buttons. There are two USB-C ports on the front of the box and one on the back. While the one on the back is for "power" I have found that mistakenly plugging in power to the front panel also worked. There is a lot of discussion on what works and how on YouTube and the AtariAge forums.
I have been thrilled playing Atari 7800 Choplifter, 7800 Dig Dug, and Super Nintendo's Donkey Kong Country, but my biggest win has been discovering Sega Genesis games! I had never had or played with Genesis, and when I discovered ports of such incredible games as StarFlight and Populous II, many hours were lost. Many hours. I am also really happy with the Arcade game support: Space Harrier and Sinistar have been in rotation. Space Harrier's music over my television soundsystem is hilariously wonderful.
SNES compatibility was added with a very nice firmware update last week. I have seen a report or two of some NeoGeo/TurboGrafx16 stuff working too. A number of sore spots were fixed, and the SD card filesystem management was vastly improved. MyArcade supports this device and is behind its use as a multi-console emulator. I am enthusiastic.
My Arcade Atari GameStation Pro via Amazon (for those who do not have Costco, its $15.00 more.)