Here is my idea:

Country Curtains has beautiful sheers.

Buy 3 rods. Where the finial normally would screw in you get a piece at the hardware store that allows you to screw 2 rods together. It will look exactly like your picture. I have used rods from pottery barn and bed bath and beyond to do that.

Wood dowels, what's used in closets for hanging clothes. I'm nor sure but think HD has them in 10'-12' lengths. Circumferences vary, but again, not quite sure but could be up to 3". Can be painted, stained, gilded, whatever. Has to be substantially less expensive than 22' of any type of drapery rod.

Here is a link that might be useful: Wood dowels

electrical conduit & appropriately sized connectors. Paint any color you want.

I once used PVC pipe then painted it gold and used a support in the middle, they also make brackets that you can't see, sort of like an elbow bracket that the rod sits on and screws in underneath the rod and to the wall. PVC comes in different sizes, I don't remember now but I think this was 3 in. diameter pipe. Home Depot. It was light weight and you can get it in any length. I glued on the finials. You can use a ball or something on the end something lightweight and either paint it or wood faux finish them. Sorry for the poor quality picture.

Photo of PVC rod (from several years ago in another house, contemporary lace swags on painted PVC rod).

We made ours out of PVC & spray painted with ORB paint and made the end,and middle supports too. We used a decorative wood piece (painted that the ORB too). They looked wonderful and were a fraction of the cost.

I was just at my local JC Penney the other day and saw lots of drapery panels in various heights that I would consider using in an installation. They also had lots of reasonably priced rods from Umbra & Studio that might work for your installation.