There are cheap windows everywhere. For mid grade windows, i'd look at Pella and Anderson's "high end" products, though Anderson's fiberglass windows look like a pretty good value to me. Marvin's entry level stuff falls into this category for me as well.
For what i'd call "good" windows, check Marvin's upper line or Loewen.
I think cheap windows are generally not much better than decent old windows. My 100 year old single pane wood double hungs, with a little attention and tuning, perform better than cheap vinyl thermal pane units. And i know that, with some care, they'll likely last another 100 years.
The trick with old windows is stopping the draft. Draft is the real energy killer - not the single pane glazing. I live in St. Louis, which traditionally has the most freeze/thaw cycles per year of anywhere in the country - decent storms take care of the icing issues.
When i looked at it a couple of years ago, fixing up my original windows became the leading option. With 40 windows in my house, i'd have spent a LOT of money buying cheap vinyl windows. I wasn't wild about vinyl to begin with, plus they don't look right with my old house. And, they'd have been cheap ones. Or, i could have spent a little over $40,000 on decent windows that seemed like they would have lasted a while. "Good" windows were another $20,000. Lacking a money tree, i looked into repairing and tuning up my original windows. I have to say - i'm really glad i took that route. The most difficult part was finding some pieces of salvaged old growth wood to replace the few broken parts i had. I'm not done with the entire house yet, but i'm averaging about $60 per window - not $1000. The draft is gone, our cold spots are pretty much gone, and our energy bills dropped off considerably.
All that said, there are still a few windows that i will be replacing (basement and attic dormers). Repair isn't a good option for every house or home owner. However, i do think it's an option that most people never really consider. High end thermal windows would perform better than my originals, no doubt. But it would take me 5 lifetimes to recoup the installation cost in energy savings.
my cent and a half's worth.
paulh