Rowasa Enema: Discounted price?

I have been prescribed Rowasa Enema for ulcerative colitis, but am unable to afford it without insurance. I can not find it for any price lower than $800. My doctor said that there are no substitutes that he can give me, that I absolutely must have this medication. He also does not have samples that he can provide. Does anyone know a way that I can get this medication any cheaper? Maybe a discount drug program or a discount directly from the manufacturer. Maybe a pharmaceutical rep? I don't know what to do.