Hi again Ash,
I realise home-builders (I include myself here) can source cheap(er) parts from the Internet and build our own. In the early days that was the only way to do it, but there were many problems due to chipsets in for example WiFi dongles not being what they claimed to be and as a result not working properly (if at all!). This led to the Recommended Hardware List, which in turn led to the guys marketing the Classic Kit, which comprises all parts from approved sources, pre-assembled and tested before dispatch and so 'guaranteed to work'. They do make a very small markup to cover their costs, but as the Kit includes the P3i Bridge board (not available elsewhere), first year software licence and support - it really does represent great value.
Regards
Peter
(p.s. Although I am a member of the development team, my interest is purely from the flight safety angle - I have no financial interest here).