Anthony, do you have any experience using the LitiHolo self-developing plates? I'm definitely going for quality/longevity, although I can't find any sort of comparisons apart from the >90% reflectivity claims. When purchased in bulk, they are about $5 each.I noticed you mentioned $15.00 per plate. Check out the Integraf website https://www.integraf.com/
Transmission type holograms are much easier to make than reflection type... maybe a good place to start to work the kinks out of your set up.
I look forward to updates on your progress.