I've always hoped that, if they were going to offer mixed bundles of GPK's and Wackys, to do the following:
Order the 5 GPK's for 20 bucks
Order the 5 Wackys for 20 bucks
Buy all 10 for a discounted 34.99!
(Assuming 5 each of GPK's and Wackys, 10 titles total)