If there are lenses available that could be used to pull the tools from you may want to consider having a shop do a short run.
I used this company several years ago to make some lenses for an application.
Akra Plastic Products, Inc.*
Look for a shop that does vacuum forming, drape or blow molding of acrylic parts. Give the company a call and spend some time on the phone discussing your requirements. The tooling costs should not be too high. I don't see this one as too big a deal if you find the right shop and do a pool buy in order to amortize the tooling costs.
* This is by no means a recommendation and I do not have nay relationship with this particular company.