Hi wacobird . . .
For the How Much - contact the vendor through the link for current quote. Probably hasn't changed much since you bought yours.
How Long - vendor trying to maintain supply so they have reliable 6 wek delivery. This seems to be working.
Round pipe? - I've been trying to talk vendor into doing this for 3 years. Maybe if you, a user, let's them know it's important to you they'll listen !