Seiko 5645-8000 hi-beat auto

This is the only Vintage Grand Seiko i can find for sale anywhere on the web and the Only one on this forum or ebay. the last one to sell on ebay sold for over £900!! i know because i was outbid   Price Reduction again! 

this is a fabulous and high quality timepiece that i am only selling as i have 2 with the same movement. i have a growing collection of Grand and King Seiko's which beat most swiss watches hands down.
Grand Seiko's are a very special timepiece made by only a few master watchmakers at the Seiko factory and only sold in Japan. they are all 'GS standard' which is more exacting than a swiss chronometer certification and can be adjusted to an accuracy of +/- 0 secs if you try.
this particular model, the 5645-8000, is the last one they made before stopping production in the very early 1970's. production was then re commenced in 1998.
the stainless steel case is 37mm diameter not including the crown which is the original GS item, it has highly polished sides and brush finished lug covers. i would rate the condition as 90% as it is 38 years old and not perfect (nothing in life is perfect). it has a very light 4mm long scratch on case under 6 oclock and a couple of very light scratches on the back of the case. the 'bezel' is not stainless steel, but nickel plated (i think) and has some brassing to it which i believe is a result of over enthusiastic cleaning over the years. it gives the bezel a slight golden hue. the caseback is near perfect with a superb gold GS medallion. the glass is unmarked as is the lovely silver dial which has applied steel hour markers with date at 3 oclock. the hands are perfect steel pointers with a virtual sweep second(8 beat).
the movement is a 5645A calibre, 25 jewels, adjusted to 5 positions and temp and is in unmarked condition. it is a hack second auto hi-beat (28800vph). on my wrist it is currently running at +4 secs a day, but i cannot guarantee that as a mechanical watch works differently on everyones wrist. as i have said, it is possible to adjust these movements to virtually perfect time given a bit of effort and patience.
these are very special watches with great 'stealth' appeal and vintage pieces like this are highly desirable.

i might consider a trade for a GS with any of the following calibres.  3180, 57GS, 62GS or 61GS

all i am asking is £550 to include shipping by Royal Mail International Signed for service.
bank wire is preferred, but i may consider paypal if charges are paid by the buyer.