You don't want to be any higher than 5.0 for blueberries.
I just found this thread but I have dealt with Nourse and they are a good nursery.
I stopped by there last year and they have some beautiful stock.
I have personally ordered those blueberries from Nourse this year. Around here that is a good price and they are known for their quality.
I have looked at Stark, Miller, Raintree and other nurseries and they are only selling plants in a 4 inch pot and some of their prices are even higher than Nourse.
At nourse your root stock will be a minimum of a foot and a half tall, better than a 4 inch pot.
One of the catalogs is charging $26.50 for their "jumbo" size plants.
If you check their website and read the descriptions of each type they describe where they will do best and you can also call them for advice on that as well.
They also guarantee their stock so there is that.
You aren't worried about getting a crop this year, just getting them in the ground for next year if you feel confident about what you are getting from Nourse I would go ahead and order from them.
The cheaper deal is not always the better deal and I have found that when it comes to buying any type of plants, berry shrubs, fruit trees, as with most things, you get what you pay for.