ProjectMu are a huge Japense brake manufacturer. If you have a squint around some of the Japenese orientated online shops, they can probably source some for you.
The discs themselves won't be "VW Golf MK5 fitment", they'll just be sold based on the size/width so should be pretty easy to source.
Alternatively, and some people may correct me here, but it might be possible to source some from a n other brake manufacturer, like AP or the likes, if the bolting pattern matches. My knowledge of 2 piece gear isn't the strongest. Also, you'd have to not mention to AP it wasn't for their brakes ;)
As far as a refurb goes, the best place i've ever used is BiggRed. Their quality of work is fantastic, but i can assure you it won't be £100
You can, however, buy seal kits, pistons, bleed nipples from them for very reasonable prices.
If this is the kit that was for sale on the forum, i was very tempted myself, but didn't want to have to change out wheels. It'll be such a capable kit with the right components :)