A quick trip to Jerry's, our local family-owned DIY superstore, and I found the variety I needed. These plastic blinds come in packets of 9, but oddly our blind track had 29 hooks, so I'd need 4 packets to do every hook. I decided to get 3 packets and leave one hook empty at each end instead. There were two plain versions at $9.99 a packet, white and alabaster, and a number of more fancy textured ones, but as the textures tripled the price again my decision was simple. White or Alabaster? White would show every speck of dust, so (with Beth's advice) I chose Alabaster.
The next decision was whether to have the blinds cut down. Jerry's offer this service onsite so you can have the blinds fit any length of window. The packet specified 84" long, but I'd already measured the drop on our blinds at a little over 82". Aha, but these blinds are not really 84" long, they're designed to fit an 84" window frame. No need to cut them down then, so I purchased 3 packets and tootled home.
After a little puzzlement over how to remove the blinds from the aluminium hook of the packaging, I got the blinds free and started hanging them. The job couldn't have been easier, just push each blind into the hook fitting until it clicks into place and onto the next one. In less than 5 minutes the job was finished.
Blinds fully closed
drawn but open
And that was that. I should have done this a year ago, but I was expecting the job to be harder.