Someone help me out. 

I am looking for a low RG ball, ideally a mid-low diff and a weak reactive (solid or pearl) cover.  Not really picky about manufacturer but I am looking for any ideas as to whats out there.

Go!

You really wont find much out there towards the entry level price point.  Most everything is high RG.  Closest thing that comes to mind is the Eruption line from Columbia.  I have a Violent Eruption which is a pearl that has the low RG (2.48) with a low/medium diff (.035 I believe).  The ball being a pearl gets through the fronts extremely well but has a hard arcing motion on the backend.  Closest thing now might be the Eruption Pro Hybrid which has a 2.50 RG (still on the low side but closer to medium RG) with a diff of .036. 

Just looked at the IQ line from Storm.  May want to look at the Gold Pearl or Black Solid.  RG is 2.49 and diff is even lower at .029.  Think that is the best you are going to find outside that Eruption line.

i have the EP hybrid
its pretty weak for a performance piece
had to take the shine off the OBB finish as it skated to much for me
i did not care for the OG EP at all, slowed down to fast for me

but the ball you are looking for is the arson low flare
2.48/.020
http://www.hammerbowling.com/products/balls/arson-low-flare

its a different animal once you remove the factory applied clean n sheen
in fact, i bought some of the clean n sheen to be able to duplicate that finish, its 3-5 boards stronger if you take the clean n sheen off

In fact, i was told by 1 of the staffers that i should drill it stronger than i normally do as it was pretty weak, so depending on what you are trying to do, maybe a little shorter pin distance is required

look for a amf heat stroke