Sorry, but my opinion is that this is completely impractical. The price range puts it in an area where not that many people can build it and your requirements are impossible to meet.
You are severely underestimating the difficulty of maintaining accuracy in rotary stages.
tan( 20 arc seconds) * 100mm = 0.01mm
Which means your entire positional accuracy budget is blown by a single rotary table with 20 arc second error (and the standard single worm tables have error in the 1 arc minute + range).
There are no imports, and there is no way to DIY that kind of precision. Your entire budget (probably several times your budget) is gone in just the rotary tables.
I highly doubt 5 axis machines that can hold 0.01mm position accuracy go for as little as 40K, I'd expect more like 100-200K. I suppose some jewellery machines make such a claim, but they probably don't even know how accuracy is measured.