Post a question in the chainsaw forum and do it yourself. It's easy.
1. Take off the side cover.
2. Remove the clutch.
3. Take off the oil pump by removing the obvious screws & other parts.
4. put it all back together in reverse order.
Why do you think you need an oil pump? It's usually the plastic gear that operates the pump that failed. You will see it when you get past the clutch. Cheaper than a whole new pump, and they are easy to test.
One hour easy for the whole project, providing you know how to get the clutch off.