I had a plumber come out and he told me upstairs bathtub was leaking due to waste and overflow. Wants to charge about $1000.00 to fix. We are desperate to try and save money. Is there any way that we could do this ourselves? We're pretty handy. I understand it takes two people to do the job. Can someone give us step by step instructions?

Is there an access panel on the other side of the wall that has the valve and drain?
What type of pipes do you have, PVC (white plastic) ABS (black plastic) steel (grey metal)?
How do you (or the plumber) know it's the waste and overflow that is leaking? Can you see the leak through the access hole?
When does it leak, when the shower is being used and the drain is open, when the tub is being filled and the drain is closed, when the tub is draining but the faucet is closed, when the tub has been filled and you get in it causing water to flow out the overflow pipe?
Where do you see water or water damage?
If you have a access hole, can you post a picture of the waste and overflow piping?