7000 pounds is $9262 USD at todays exchange, and depending on provenance, numbers all correct and BSAOC or VMCC verified, service records and all receipts and documentation of work done, Then in IMHO thats an okay deal. Not a bargain but in the world of classics is up on the upper register of Retail prices. So, assuming all of the above is fair. But failing any of that,, price.value drops significantly.
All the old farts around my area are generally cheap B*****d's.... Ooops,, I mean economy conscious Vintage bike consumers. Good luck in neck of the woods. When I was actively building and selling bikes it was rare a local bought anything.
The bike wit the Green tank sure does look tidy and nice I think, but it does stick out the Trials/off road large front wheel with Knobby (Which is okay on certain models) but clashes with the modern tread street tire in the rear. I like the high pipe on it, not too sure on the fenders,, might be correct on a offroader/trials bike but the road going painted fenders are affordable from Indian vendors (Were virtually un-ob-tain-ium for years) If I was serious about the bike would require tons more details and a on the ground FPI from some one, plus research.
The red 'un on trademe is a civilianized M20 and while very nice on its own,, I would think would not be quite as valued as the ZB. 3 speed or 4? Flat head or ZB or B33 top end?. Again, for the US the trademe red 'un is well into the upper retail spectrum and I dont see a US buyer paying a premium for it and then paying shipping on top of that. But that may very well be fair market value in Oz and NZ.
I like and collect those early style bikes, to me they are the sexiest style and really represent a true classic. I have other bikes of course, but over the years I have collected a number of "Keepers" that are in that style. (48 speed twin,52 Blackbird, 47/48 Norton ES2, Several BSAs and even a 1947 Famous James w/ 98cc villiers).
I have some other Triumph preunit rigids as well (Will be sold) and my take on these early bikes is that for years only true nutters for old iron collected the old rigids and plungers. Prices tended to be low for parts and projects. But at some point, prices climbed and it seems that people just want something really old and antique. Rigid PU Triumphs have seen huge increases in last 10 years and now, a bare frame is $800-1500 USD and of course I paid less for whole bikes not that long ago.
I had a shop client years back I tried to talk out of purchasing a 1940s AJS. He didnt care about the issues on it, He was just super excited to have some bike from the 1940s. I think that kinda is the mindset for some people. The reality of restoring one, and maintaining it is significantly challenging, but that does not seem to factor in their decision.
Thats my take on this from the cheap seats...