I took one class that I considered essential. It was paper piecing. I had bought several books of patterns using that technique, but I couldn't figure it out on my own. The LQS had some required equipment (small cutting board and rotary cutter, plus add an eighth ruler), and required us to buy a pattern that interested us, plus the fabric needed. they strongly suggested that we buy the pattern and fabric from them and offered a 10% discount. The instructor started with a small sample block - a triangle pine tree with stem. After we finished with that, she helped us with the pattern that we had chosen. I didn't finish my project, but I did learn the technique, so I was able to finish it on my own without a problem.
OTOH, my sewing machine dealer is different. I bought an expensive machine. It came with a few classes, which I took. Then about a year later, I needed to make a buttonhole. I couldn't figure out how to do it, it was totally different from my last machine. I went it and asked the owner to show me how to do a buttonhole again. He wanted me to sign up an pay for additional classes, but finally relented and showed me how to do it. And in the mean time, I had taken both of my machines to him to repair/adjust. The dealer also has clubs where you pay a fee, and apparently are required to buy new embroidery patterns each month on top of that. I did take a fairly expensive class ($50) from them later, only to find out that on top of the class fee we were required to buy the pattern that was the subject of the class (I had expected it to be included in the expensive class fee), and they didn't even have it in stock.
Our quilt guild offers some classes, some taught by a guild member and some taught by an outside teacher, often the speaker for the monthly meeting. The fees are fairly low, and it's more of an excuse to get together and snack. One was lone star in a day, and I almost had the lone star center completed in the 6 hr class. One was on a new curvy ruler. Several used commercial patterns, and the fee was structured to include the pattern. Sometimes we'll get together to make something to sell at our quilt show.