It costs HOW MUCH to take guitar lessons???

I've been fairly decided on the idea of getting guitar lessons for Isaac for Christmas. I was eventually going to get around to checking the cost, but, remembering the $5 a week it cost for piano lessons when I was a kid, I figured cost would not be an issue. I keep forgetting that "when I was a kid" was 20 years ago. So John was talking to a friend from work at our Halloween mask making class at Swan Lake last night, and she said her son just loves his lessons. He goes to the same place I would send Isaac. His lessons cost $70 a month. That's for one 30-minute lesson per week. So, what do we do? I'm debating whether I could learn guitar with him at home, for free...but part of the point of the lessons is for him to get out of the house, and perform with other kids, and for him to be taught by someone perhaps a bit more patient than his mother. I can't imagine finding $70 a month to spend on this, especially when I was going to get art lessons for Simon, which surely cost this much as well. Argh. If I have to revisit my food budget and start trying to extreme coupon again, I will cry. Give me your opinion - is this something I need to do, or is this an outrageous luxury that the kids can do without? And what about the school band? Can I dual-enroll him in band and get free lessons at the school?