With cheap Filipino 1911s going for $400, I fail to see the attraction of a mix master 1911 with a substandard slide for $1,000.
What the CMP might be selling is what I have been passing on for less money in gun stores for years.
If the CMP had matching and correct 1911s, I could understand huge prices but a mixmaster isn't very historically interesting and since you can get a better 1911 for less money, curiosity seems to be the only value.
I learned to shoot with an unissued Remington Rand. It seems really stupid now. It was a nice gun, pretty tight and accurate but it hadn't been rearsenaled a few times. I imagine a CMP gun will be very sloppy by comparison. Although the Remington Rand was nice, I have shot better which is why it was so stupid to break it's cherry.
I haven't shopped recently but I bet there are plenty of good series 70 Colts for around $1,000 and that is a superior 1911 to anything surplus.
The last 1911 I bought was a $120 Norinco frame, slide and barrel project. It is metallurgically superior and M1911A1 spec. I won't feel bad about peening the rails, squeezing the slide, cutting it for a beaver tail safety, stippling or anything else I might want to do. The best part is I'll be able to do all of that for less than $1,000.