There's so much good used film equipment on the market now at fire-sale prices, ...
it's hard to justify buying damaged goods at any price.
If it's fungus, the lens is shot and can only be revived by replacing the affected elements.
Fungus lives on the magnesium fluoride coating. Its waste product is hydrofluoric acid, which etches glass.
Couple this with the fact that fungal spores can lie dormant indefinitely, and will infect other lenses in the vicinity, and you have a recipe for disaster. I wouldn't take fungus-damaged lens if somebody forced it on me.