I don't think they're assembling the boards by hand, I think they're having them produced for them by some Asian company. I think you mentioned yourself in this thread - or it might have been someone else - that this is quite doable. Are you saying that if I want to have 1000 boards produced by some Taiwanese company that I can't have 10 boards to begin with, to see what the standard is like?
Obviously. But I dont think assembly is the issue here. Contrary to D&T, Im convinced no matter if you have to
order 1000+ or 10k s-asics that you will first receive a single wafer, or at most a single wafer run (usually 4 wafers) for testing, characterization, to validate your PCB etc. The biggest cost is the mask set; once you have that, you'd pretty much pay standard wafer price, but that still isnt cheap for 100+ wafers, so it doesnt make sense to bake 100s of wafers before being able to test and validate your first chip. Particularly since you wouldnt be ready to sell your product; thats not specific to BFL, anyone would have to test and debug their prototypes first. Its not good business to sit on 1000 processed wafers for all that time.
In short; my guess is BFL have ~100 chips now from a test run, possibly they are assembling them on boards themselves, and it will take at least 8 or so weeks from the green light before they receive the first of the volume production wafers (then there is wafer and/or chip testing, cutting, packaging, mounting etc) which they would probably have someone assemble on the PCBs elsewhere.
As for financing; Im sure they have had to pay Altera (or whomever) a considerable amount already, but you usually dont pay 100% up front either. It probably boils down to them having paid for the mask set and the test wafers, but not the volume production yet. Either way, they will have bills to pay and its good to be able to show investors initial revenue sooner rather than later.