I have ordered from Musser Forest in PA in the past. Usually 1-3k annually. I have been really impressed with their quality, size, price.
The big thing when purchasing conifers IMO is plant as soon as you can dig a hole in the spring and order from a nursery that cuts and ships them to you within a few days. No cold storage like you get with a lot of nurseries/conservation districts.
I switched to a local pick up place but used Musser for 10 yrs or so. Plant early, and dip the roots in Water keep/water sorb and I've been close to 100% survival most years.
Only hiccup is if they have a late spring and you have an early one and they can't cut when your spring arrives :)