oil leaking

Hi,
I have a 97 Sable, 3.0 DOHC ( I think).

There has been some engine oil leaking.
I took the car to the mechanic and he said there are two leaks.

1-Camshaft synchronizer is leaking and this repair needs immediate (or quick) attention. Part 137 labor 110.From parts the mechanic said that camshaft sensor will be removed as well.
2-Oil pan gasket needs a replacement parts 120 (gasket + new pan) and 370 in labor.

Since I am a student and budget is tight , I wanted to give it a shot and try the repair myself but after consulting the Chilton manual I couldn't find any information on how to replace the camshaft and it doesn't even mentions any seal I need to install. I have done much repair myself but with this one I am at a loss.

Could someone tell of how immediate this repair could be necessary?
Are those prices normal for such a job?
There are days when leak is evident and there are others where only a drop or so comes out, its not that oil leaks like from an open tap.

Thanks