Have had the Ser 70 and Ser 80 Gold Cups. Not thrilled with the Ser 80/90 anything.
I bought two Ser 70 Gold Cups two years ago within six months of each other. Both in the same Serial range and both here in WY.
First one (June 2010) had been shot (98%) and did not have box or papers. Price was $1150. Second one ( Dec 5, 2010) was NIB, with the hanging tag and oily plastic wrapper still over the gun. Price was $1100. #1 I got from a neighbor at a Show in Rock Springs. The second one I got from a gent at the Casper Show. Both were made in 1977 and the second one had been in a safe since being bought. Second one is still in my possession as it was a Birthday present from my wife. Got it on my BD too.
Prices seem to have held in the $1200-1400 range at the shows and on GB.
Military 1911/1911A1s are all over the price range depending on what they are, manufacturer and naturally the condition.
If you are looking for a great reliable shooter you would be hard pressed to find something better or more accurate than the Series 70 Gold Cup or the 1950s-60s National Match (pre Gold Cup).
Thom Braxton
SWCA #1474