The June Taylor spray is the cheapest...but it is also hard to get the over spray off of other things... I am told that the other brands are easier to clean up.
I lay a cheap $1 shower curtain on the floor to catch the over spray :wink:
The basting sprays do keep the sandwich together very nicely. I still pin around the edges, because of the amount of handling they get. I have not machine quilted anything larger than a 50" X 72" yet, but it held it together pefectly.
There are some here who say that it still held after a few months, but I do not remember which brands they were using.