Actually, it's cheap. Use code "zorn" when you check out, and you get a gift certificate for future Yoshi shows equal to the amount of your Zorn purchase. In other words, the tickets are FREE, assuming you're going to another Yoshi's show before September.
I agree it's expensive. Yoshi's is greedy building that enormous place and losing money. But look at the lineup. ALL big name guys you will only see in NYC brought to the west coast. so... it's cheaper than a plane ticket.
Sun 3/15 @ Yoshi's San Francisco
Tue 3/10 @ Yoshi's San Francisco