This is very much a frankenbike. As noted, the headeset, crankset and pedals appear to be Dura-Ace EX, yet the rear derailleur appears to be 600EX and the front hub has a 600EX skewer nut. The rear hub is Campagnolo Record. I don't recognize the brakeset.

Top tube cable clips in conjunction with shift lever braze-ons were not uncommon during the mid-1970s. Many frame builders were still reluctant to braze fittings onto the top tube due to the lighter gauge tubing. However, top tube cable tunnels were common by the time that dual bottle bosses and front derailleur bosses came into common use. I would also have expected recessed brake mounts by this time. This makes it hard to peg the timeline and suggests the frame is custom or owner built.

However, I agree, that is a very good price.