I used to use ProMix exclusively, and you're right Terese, I used the compressed bales. I liked it, except that it was so hard to wet, and if it dried out, hard to re-wet. But sometimes I've used Fafard, and last year and this year I'm using Sunshine Mix #4. I don't grow as much as I used to, and I'm old and decrepit and have trouble carrying those bales, so I haven't bought the compressed bales for the past few years.
http://wormsway.com/en/SAM930D
Around here the big box stores only carry Miracle Grow, not any of the professional potting mixes. I buy my mix at a local hydroponic store. If you try those, you probably will find a good selection.
Another option: go to a reputable nursery, ask what mix they use for growing their own seeds and cuttings. They might sell you a bag of that. That's how I bought my Pro Mix for a few years, and my Fafard mix a few more years...
Karen