Been watching these for a few years.
!983 and prior are typically going in the $1400-1700 range depending upon condition and whether they were redone.
Newer machines without "asbestos" lining seem to be anywhere from $1650-2400....again depends upon condition accessories etc.

Why do the post 83 command a slight premium? Is it solely due to lack of asbestos or are there other factors to consider?

Power Switch, top pressure valve, etc....I guess

Here in Switzerland, the magic treshold is 1200 swiss francs: auctioned with a starting bid below that, and people jump at it immediately. starting above, nobody bids (but everybody encircles it like a vulture). Selling price is usually roughly 1000 francs, maybe more if the machine has new gaskets.

i think this price for an old cremina is justified, for what you get. the new machines are way overpriced: you get welded stainless steel instead of brazed brass, and some off-the-shelf pstat. the old olympia pstats were huge, but very accurate, and can be adjusted without tools. the new ones go for 2500-3500.
sometimes you still get lucky: i know of a cremina which was found on the curb, and one that was bought in a thrift store, for 50 francs.

some very old post-67-creminas still have a socket for the power cord on the side, this plug is very, very, VERY hard to find if it has gone missing.

the asbestos is no issue. but make sure the rocker switch rocks both ways, and the oblong roller hole in the group is still intact. dont worry about wallered lever fork holes. forks are easy replaceable, unlike the switch or the group.

Thanks to everyone who gave me input. I pulled the trigger and picked up a 1985 Cremina in very good condition. Only missing the filter basket. Tested it before I bought it. Seals are good, produces steam and I pulled an adequate shot using a Pavoni Europiccalo basket. I paid $1,750. I feel like I paid a little bit of a premium but willing to do so because I was able to see it and test it.

Congrats! Enjoy your machine.