Wow, I got 100% light and credits were never a problem for me. I found so much stuff that I didn't ever buy anything for my party members, so I just had a bunch of credits and stuff that I never used.
I have only played light and can't wait to play dark! The only reason I played light was because I was slightly more light after Telos and I wanted to get into that cave in Korriban, and I thought what the hell, might as well stay light.
I never played light in the first one, so it was sort of fun. (In the first game I was mostly neutral until I found out I was Reven, and then my character got evil fast). Although when Kriea killed the Jedi I had gathered, I was sad, but then I saw Master Vrook, and I thought "haha, he's dead." He was an ass. I can't wait to kill him in cold blood, if you can do that. I hope you can do that.