Oil pump?

Ok, I bought a 04 400FA used. I have had nothing but problems with it....
Replaced the clutch because it was slipping. Got it back month or two later it started to slip again. When I brought it back I was told that the oil pumps is bad and it needs to be replaced.. Something about the hi low pressure valve not working. They did some work to try to make it work. But they said I needed to replace the pump. Ok I understand that, I was then told it would cost $1400+ to fix it. I did a little research and found out that pumps cost less then 200.00. I called them up and asked why 1400.00 they said I need to replace the trans as well because you can't just replace the pump.....

I am tiered on of feeling like I am taking it without lube.... I have blackish smoke coming out the tail pipe and when I put gas to it it spins (clutch) and screams... I don't want to fry my clutch again.

Is there anything I can do. lucas oil stabil or am I just screwed

Thanks for the help