[phenixbb] Modified peptide library generation

Dear all, Sorry, this maybe a somewhat off-topic in this mailing-list. I'd like to generate a virtual peptide library which contains kinds of peptides with a modification of non-natural amino acids. In my case, the non-natural amino acid is folic-acid conjugated-phenylalanime. The peptide-length is varying from 6aa to 15aa, for example, with one non-natural amino-acid and a random amino acids. Does anyone know the best way to do it? The commercial suite, MOE, is too expensive for me to buy it, although it can generate such kinds of libraries. Best regards, Hideyuki Miyatake