If you have a H&M or Mathey, they can be rebuilt. Order new gears and have bushings installed when the old gears are replaced. A Mathey or H&M should last forever if you don't roll over it with a truck.
i wouldnt be the best advocate justthought if your on a budget cant you find donations or fab a beveler to get by with from a wheel hub of a car ! would be good exprience for the advanced students ! as a student myself! i see my instructor take donations and fab stuff! and i read about the pipe beveler! it's an idea when the money is skinny!