If it's a 91/30, AIM has bayonets for $12.95. The 91/30 ought to have a hooded front sight (unless of course it's been Finn upgraded with a stacked blade.) The M91 bayonet is much more uncommon to find and usually run around $60$75 if you can locate one. The good news is that the 91/30 bayonet will also fit an M91 if that's what your friend has.