Alternatives to el cheapo tension curtain rods
We have windows in the corner of the eating area of our kitchen. They have cellular blinds, and when we bought the house they also had curtains starting about half way down the window. So the blinds just go down to the curtains, and the curtains cover the rest. We like it this way, because it looks nice(ish) and it's nice to have the light from having the blinds up while still having some privacy from the street with the curtains closed (the street is below the house, so you're looking up from out there and really can't see anything inside with the curtains closed).
The curtains are on tension rods, which is kind of annoying because on the larger window (roughly 70") the rods tend to sag in the middle. It's just too long of a span, it seems. I've looked at every hardware store around us (both national chains and local stores), and all I can find is very similar extremely cheaply made rods. We can't use mounts that go outside the window frame on the wall, because in the corner where the windows meet there's nowhere for it to go (there's about 1/4" of wood on each side).
Any ideas for a better solution? I thought using a dowel with a pole socket like you'd have in a closet might work, but I can't find pole sockets smaller than the ones for the closet, and those are way too large (a dowel that size would look ridiculous and also wouldn't fit through the curtain). I'm not sure how else I could mount a dowel there. Maybe someone knows of a place to buy tension rods that are made of better material?
We're getting ready to sell this house in a few months, so I probably don't want to go to extreme lengths, but I'd like it to look nice and be sturdier than what we have now.