Anyone can bore any pulley to any size.
Usually, UK suppliers charge 2-3 for boring to whatever.

Generally,
*You* cant get better or equivalent for same or less money, and typically end up paying a lot more for it.

Likewise;
We, or some of us in the industry,
make 5 axis parts for 10$ an hour, qty 1, or 2, and are very sure to do QC on their critical dims.
We have to do make-up parts, so we get the next 2000 part order at reasonable pricing.