I love making buttercream. I bought Wilton's buttercream for the Wilton class I took just so I could see what the consistancy of the icing was supposed to be like. It was nice but it taste aweful!! So then I was on the lookout for a great recipe and found it. Once you get it down it really doesn't take that long. I just hate the clean up...even though I put a towel over my mixer and use the shield that goes on the bowl, I still have sugar everywhere.
I know BJ's doesn't sell it. Do you know if Costco sells it? I'm curious and am interested in checking it out, despite what I've heard in my classes.
For practice icing, you can just make buttercream with straight Crisco. That's what I learned to over 30 years ago. I'm ancient! It can sit in a container without refrigeration and be used and reused.
You won't have powdered sugar everywhere if you beat on low and don't increase the speed until you've added all your liquid. It's the fast beating with a lot of powder that messes up the whole kitchen!