There will be pre-assembled units, at probably the same price as the kit - because they will be done in larger quantity by people with a better supply chain than me.
I’d take at least 2 pre-assembled units, maybe 3 if the price is on the lower side of your estimate. Maybe even more: they’d make a great stocking stuffer for my MIDI-nerd family and friends!
And at the risk of pissing off many people on this thread, why don’t you charge a bit more for the pre-built one, even if the costs are the same to you? You need to make some money at some point, no??