eBay and Craigslist finds

Regal, all inc. that bike costs 420/450 pounds, + Tax (customs), let's say another 40quid.
In the end you're still under 500 pounds for a complete bike, NOS.
The frame alone would sell for nearly that, it would sell for at least more than half... believe me.
You'd still have the rest of the components to either keep or make profit on.
Maybe shouldn't be sharing this, but can't be arsed atm to do it myself.
It's a win win situation.

Import duty on bikes (even if they are used) is 20%. Then VAT on top, so another 20% plus handling fee of £15.

A bit more than £40 I'm afraid.