You can purchase a frame like that from a well known London dealer for £1000. Take the price of a respray and decals off that sum, and it will give you a negotiable starting price. Then get some idea of new components and knock 80 percent off the price of new parts. Bare in mind that thing are always quoted as "they're going for" when what is really meant is "they are asking for a said price" which is a hell of a lot different to "they are going for such and such price." Asking is one thing, selling it, for the asking price, is another thing!