I think $150 for 5 years would be a good happy medium. Most forums don't last 5 years, nor update add-ons regularly, so would probably be a net gain for Andy and help fund his up front development costs for new add ons.I had already bought it once for another forum. Andy is ok also the price. I noticed that his additions never made mistakes.
But I think it's better if he offers $120 five years.