I'm targetting under £1000 because I think that it could actually be doable. So far:

• Screen, controller and main UV lamp: £130
• Manta M8P, CB1 and 8 S6609 drivers: £80
• Motors, 4 leadscrews, 2 ballscrews and accessories: £190
• 24v PSU: £20
• HGR linear rails from AliExpress (X: 2x500mm Z: 2x500mm R: 2x300mm): £160
• Roll of PET: £40
• 8 resin cartridges: £80
• 405nm 3528 120/m LED strip: £10
• 50.8mm diameter cylinder (polished stainless steel): £30
• 4kg of PETG: £40
• 26.9mm galvanised tube (8x800mm): £30
• 6mm Tool Aluminium Build Plate: £30

Total: £840

While "The Unknown" has the potential to increase the price, there are also opportunities to save money, such as the roll of PET, using 1 ballscrew instead of 2 (cantilever vs x5sa like z axis), MGN rails for R and X, and savings in the hypothetical resin cartridges. 

Those cartridges are certainly a question mark since the resin might slowly negatively affect parts printed with standard FDM materials, and the cartridges contain the mechanisms to deposit to and recollect resin from the lamination film, similar to a tonner cartridge for 2D laser printers. There seem to be a few people printing resin vats so that gives me hope that I can get away with it.

Anyway, it's very unlikely that "The Unknown" is double price, meaning that a VLM solution has a high probablility of a £1700 upper bound.