IMO, bags are not the best choice.
I like hard cases. The old Oconnor style with the spring loaded bottom that kept the tripod from moving around was great. Many of these are 30 years old and still going.
The one problem is that most of the sticks people are using are a lot smaller, and don't fit well in these older cases.
Building a hard case out of irrigation pipe wouldn't be very hard.
On the issue of dead zippers and tears. Try going to auto upholstery shops to get them repaired. Jeep soft tops are full of these big zippers, and most of these shops can fix these no problem. They could probably fix tripod bags too.
Scott Sheriff
Director
http://www.sstdigitalmedia.com
"If you think it's expensive to hire a professional to do the job, wait until you hire an amateur." ---Red Adair
Where were you on 6/21?