I'd happily buy an accelerator for my real amigas if one was made that was less than the $1500+ the classic ones go for at this time. That being said I'm a realist and understand that the small demand and resulting the small run size will probably prevent that from ever happening.
I'd buy new hardware Amiga OS 4 specific hardware if it was cheaper as well but that's also unlikely.
WinUAE is probably my only chance at running OS 4.