I have designed and built some really funtional and lightweight kayak carriers. I wasn't interested in paying for a yakpack and had some ideas that I thought would work.
Ultimately, they work real well. They fold up to the size of a cantelope mellon and have padded shouldler straps as well. I wouldn't want to walk much more than 5 miles with them (which I have done in cali), but that is simply due to the weight of a kayak and full gear.
I made ten of them and I think I have two left.
I live in Boulder, let me know if you have interest. I sell them for $35...