The serial numbers during that time were arbitrary and had no bearing on manufacture date or production number. Late 60s to early 70s is actually a pretty good guess.
Retail would have been much lower than an American equivalent. Probably about 1/3. I don't think any price lists exist from that era.
As far as value goes the only concrete way to determine this is to sell it in an auction style format. If you do like the guitar it's actual value to you increases, at least to you. Some of mine I consider priceless although the market would differ.
Pics would be great! If it has the trapezoid pickups on it I distinctly remember them sounding pretty darn good.