I did 2 where it was $5 to start, $5 for any missed month. I ended up paying about $15 total for each, including the starter fee. Then one LQS switched to $2 start/missed and giving you 2 pieces of fabric. You then used your stash to fill in the rest. It was okay, but I couldn't keep up with it. The other LQS switched to where you had to pay every month and just had to pay more if you didn't finish.
My feeling is that I either don't want to be penalized at all (so where you pay for the whole club and just show up when you can) or if I do complete the block, I want to get the next one free. Not pay less. That's not fun for me. And also the I have to make a block now or else mentality isn't fun either