How cheap is too cheap for an agent?

[Greg Clark]

I'm brand new to REI and I am wondering why an agent would want to work with me on homes that are priced in the $20k range. If they make 3% commission, but finding a $20k house takes about as much work as a $100k+ house, wouldn't they be discouraged from helping, or perhaps not be particularly helpful? It just seems like it would be in their best interest to spend their time elsewhere. I've read a lot of material and no one seems to have mentioned this. Or maybe they did and I missed it. Any insight would be greatly appreciated!