I need to do the oil pump on my 2000 Z24 soon. I can't find just the screen, and I really don't feel like buying it and the pump from the dealer for twice the price I can get just the pump for. I was also told that the oil pickup tube can collapse in? If mine is, where can I get it?

A little background of the problem:
I got the car, and the oil light came on after a week. I changed the oil, and it was black. I put in Peak synthetic 5w30 and it stopped comming on. After 2 months I did another oil change and put in Castrol Edge 5w30, and now the light is comming back on everytime I make the slightest left hand turn. I was told it could be the pump failing, or the oil pickup tube collapsing. Could it just be the oil, since it started comming on right after I switched to Castrol? Car is a 2000 Cavalier Z24 2.4l with 188,000 on the engine.

http://www.napaonline.com/Catalog/Result.aspx?Ntt%3doil%2bpump%26Ntk%3dKeyword%26Nty%3d1%26N%3d599001%2b102000%2b50012%2b2012016 I entered your cars spec 2000 z24 (assume 2.4 eng) but anyway like two minutes here are parts PLUS the screen assembly you could not find.Scroll down the page pump and parts are available all day.

The Sealed Power pump does not come with the screen or the pickup tube. I emailed them about it after I seen it on Rock Auto.
Im just looking for the screen and the pickup tube. I just dont want to pay twice as much from the dealer