I think that for starter homes, apartments are the way to go. Obviously this won't be your Sim's permanent home, unless you're playing a single Sim, but some can be dirt-cheap. There's one in Bridgeport that's only §4,237(or around that), which is quite nice. If you make your own apartments, you could pay practically nothing for it by putting most of the facilities outside the apartment.
As far as middle income houses go, I think that §35,000 is a good base price, whereas §80,000 would be about as high as I would be willing to go.
I would think that §80,000 is a bit low for a high income house, so I think that there's another wealth level inbetween them. I call it the top end of the middle income area. These are slightly better than the middle income houses, not in terms of furniture but space. These would top off at about §150,000.
High income houses start at §150,000, with noticeable features being more space and better furniture. There isn't really a cap on the price, but realistically, the most that it should be is §500,000, unless it's for a multi-generational game or a collection museum or some other such thing.
Well, there's my thoughts on house pricings.