Where can I buy gentian lilac?

At most any pharmacy. Gentian Violet is a great anti-infective; for people and animals. I hold used it for years. I hope this helps.
It is a adjectives antifungal topical treatment, so it should be available at your nearest drugstore, try Walgreens or Longs Drugs.
Medical supply house.
You can buy this at a local pharmacy or herbal supply store or even online.
at most pharmacies.