www.strongbags.com
I don't work there and don't have a $.05 in this comment - but, I used to have the purdyneat bag. It did very well for many years, but it was time to move on. I've used the strongbag for two months now and I must say it kicks as$ on the PN bag. Much cheaper, lighter, and just as sturdy where you need it. PN zero fuel weight is pretty heavy and not all that metal was needed in my opinion. SB figured that out and put metal on the bottom and heavy duty plastic around the frame which is just fine. Many other features that make this bag better too. I'm glad someone else finally came in with a new bag.
Costco bag has big wheels. Two of them are a tight squeeze in the 300's. Not sure if they're such a good deal anymore either. I think the unimited exchange program might be over but not sure.
Anyway, strongbag is a great bag. 737 guys started the company by the way.
G