I have the RG35XXSP. It will play PS1 and Dreamcast games very well but I wouldn't recommend it for those since it has no analog sticks. The RG34XXSP does have sticks but the screen is slightly smaller due to the different aspect ratio, but I think it has the same chipset as the 35 and is slightly more expensive. They're a bit on the small side though but that doesn't really bother me.
I also have an AYN Thor (it's dual screen) but that's not even in the same ballpark as $100.