Can someone give me some suggestions for a 1:1 substitute for a discontinued hair product?

This seems to be the only hair product that works well with my hair. I have tried MANY. My wife also gets a lot of use out of it and we both love it. A little goes a LONG way, fortunately so one of these containers will last a few months. Now, I can only find it on ebay for like $60. Thats not really ideal considering when she first bought it years ago, it was maybe like $10-$15 bucks. And surely they'll eventually disappear. Its discontinued and thats why Im here.

Is anyone familiar with this product and able to give me a recommendation for what a good replacement/substitute would be for this? Thank you in advance!