Any ideas on easier or cheaper ways to fix this would be appreciated very much!

If the ridges are raised as you said,I cannot think of any way but sanding,sorry.You COULD try another coat but I do not think it is going to fix the problem. In some states real painters must be licensed, in which case you could recoup damages, it does not sound like this character was licensed.

Thanks for the reply. I wish painters had to be licensed here, but they don't. This state is one of the easiest to get ripped off in, because they don't require licenses for hardly anything.

You may not even be able to adequately sand those roller marks out by hand either. It may require an orbital or electric finishing sander. Sometimes depending on how widespread the roller marks are, skimcoating may be quicker. The problem is that when you sand, you think you are getting it done but then when you put a shiny paint on the walls you notice that you didn't sand enough and the roller marks are still visible.

paintguy, couldn't something like a high-hide primer be used after sanding to make sure it's all back to an even tone? Even something maybe like GARDZ?

And to clarify, I meant use GARDZ and then a primer, not use GARDZ as a primer. I was writing in my own personal shorthand...sorry.

I don't know really. Usually, paint or primer, even if it is thick or high-build, isn't enough to cover up flaws, but it is possible if the flaws are minor.

Thanks for the help, everyone. I tried sanding, but it didn't work out. The "painter" who made the mess, who does have some drywall experience (mostly taping & mudding seams), agreed to come back and skim coat the walls. He finished the sanding last night. I don't know if this is what skim coating is supposed to look like or not (the wall still shows thru in some places and other places it doesn't show at all) but he swears what he did will correct the problem. I hope he's right.

let us know....I am curious since I have the same issue on a wall in my home!