We just replaced all the blinds in our motorhome. The ones that came with the coach were true day/night shades and had the strings for tension. Probably great when new but, like everything else, they wear out. Rather than replace in kind we went to Home Depot and ordered MyBlinds that have a latch in the center of the blind that keeps them in whatever position you set them in. Our coach has some different window shapes (wide short windows, narrow tall windows, etc.). We re-placed all nine window blinds for less than $1000. They may not last as long as the original blinds but ease of use is so much better! They are not day/night but we always had the blinds either open or closed, anyway. If you watch the big box stores they have sales quite often.
2008 Safari Simba 37PDQ
2012 Fiat 500 Abarth