I'm really struggling at ascertaining realistic comps for properties I'm looking at. A perfect example is the home I'm looking at right now:

Foreclosed - Sale price of 112k (Previously sold for 154k in '05)

House is in reasonably good shape, the basement needs finishing, it needs a few appliances, and paint throughout. I'm sure there are a million other finer things needed, but that's the overall gist of it. It's in very good condition overall.

I'm trying to find comps to see what a realistic sales price would be for it. Two houses initially stuck out to be on Zillow - Both 1 block over (no big change between the two streets), both sold for 140k. These two homes are pretty similar to the foreclosed one. I felt like I had a bit of a general idea at this point.

Then I look and see a few more houses on the same block that sold for 90-100k.. I look at them and I can see no appreciable differences between those and the ones that sold for 140k. Same street, houses look very similar. There are slight differences between them, but I don't see 40-50k in differences. 

I'm working with a realtor who has been helpful, but I'd rather not run to him every single deal I look at. I'm hoping I can learn to do comps myself so that I can only send over the ones that I think are a good deal and see what he thinks. I'm really struggling with the variations I'm seeing in price, though. Often times I don't even see comps for a house that have sold within the past 6 months, making it even harder.