I have a stone foundation and water comes in 24/7. I have to repair it some how. Any cheap ideas how to fix it?

Would need to know a little more about the problem. There is a product called RedGard that can be used to seal over stone, concrete, etc. but don't know if it would work in your situation.

The hole is about 3 inches in diameter and it stays wet about 90% of the time.

Try hydraulic cement. It should be available at most building supply houses. It works very well for filling that type of hole. Good luck

If you have one hole 3" in diameter it is likely you have many other cracks too. Hydralic cement is a great suggestion for the hole Google but be prepared for other sealing products for small cracks. Here is just one DIY Basement Sealing, Basement & Foundation Waterproofing System, Waterproof Your Basement