If you look at the small current 'Amiga' user-base it seems that most of us are into Classics (going by recent polls), what's left is split between AROS/OS4/MorphOS.
So the market for a new 'budget' OS4 machine is basically Classic users who are interested in OS4 but can only afford (or want) to spend a certain amount and users outside the current scene (eg x-Amiga users or just innocent bystanders). I guess existing OS4 users will also have a certain interest just for the novelty of having a portable OS4 machine.
Either way, I'd say their market is going to be pretty small unless Hyperion really step up the pace and quality of OS4 development.
Personally, I'm not (currently) interested in buying a new OS4 machine even if it was for $50