There are a variety of research chem sites that can likely provide this fairly quickly. Mike Arnold has some good products, I imagine that his anastrozole would be good, too. Also, there are a number of pharmaceutical sites that do not require prescription. You might think about talking to an all day chemist ry professor on that one, for example.
DIM is an OTC supp that can help, but is usually only good for a few points.
Now another OTC supp that I have had good luck with is Arimistane. It is touted as an AI and seems particularly effective, based on my test results
here. Note that in a very short time, it brought my E2 way down.
Your best bet is pharma followed by research chem followed by OTC, IMHO.
Just my likely way overpriced two cents on that.
PS - we typically wont spell out a source, but if you read between the lines and have google skills, you can likely find what you need.