FYI, I bought SPB 2.1 back on Jan 2 which is just outside their 90 day upgrade free policy. My serial for 2.1 didn't work. I sent them an email and they replied with a link for a free upgrade.
So if you are outside the free upgrade window, give it a shot. They replied in under an hour. Here's the link I used to send the message.
http://www.spbsoftwarehouse.com/support/question.html