For what they are, D-rings cost a lot on eBay or from RIB shops. Once you factor in the price of proper two-part glue, it adds up, especially if you have a few to fit.
But it’s fairly easy to make your own D-rings for your IK to attach gear, thigh straps, footrest mounts and so on.
You can buy metal D-rings by the sack-load, and round PVC or Hypalon patches or off-cuts are as easily bought on eBay. (‘Hypalon’ is the same synthetic rubber as Gumotex Nitrilon and Grabner EDPM). Or you may have spare patch that came with your boat. A D-ring doesn’t have to be round but it’s better if corners are rounded.
Pictures below show how to make your own D-rings.
This page shows step-by-step how to apply any patch properly.