Well, at first, it will only be available through the Kickstarter program, which accepts Amazon payments. Later, it may be possible to pay with Western Union.
There are many "DIY" versions of linear slides - we probably have a dozen here on this forum alone. So there's no problem there... the nice thing about this system is that it is factory made in a way that would be very difficult to DIY. There's some discussion of that over at hackaday
. Check it out!