Civi 4.6.4 and WP 4.2.2 I have an Event(3 day Conference) with 6 pricing options. The first is for the Full conference with different prices for a Member, Certified Member, and Non-Member. AND there are 5 other price options for daily activities with pricing options again for Member, Certified Member, and Non-Member. I can't make any of the pricing fields required since they can choose any of the options. My problem is, though, that they must pick one, but don't know how to make this happen.
My non-code way of (almost) solving this is to include a zero price "no-selection" option such as "I not attending the full event" or "I have selected a different workshop" in each price field and make each price field compulsory.
My experience has been that people forget to tick anything, rather than deliberately choose not to make a selection, so forcing people to make a selection for each field has worked for us.
I should point out that I have only done it with 3 sets of price options, and I didn't get any flack about making people tick so many boxes. I don't know how people would have reacted if they had been forced to make 6 "selections".
The "almost" in the first sentence is because each year we still got one or two out of 1000 people who chose the "no-selection" option in every set. I set up a smart group for people with a registration value of zero and sent them a standard email alerting them to that fact.