I would encourage you to think about head room, just for at least sitting up in your tent. Even if you don't plan on spending much time in it, having the space to at least change clothing comfortably can be nice, or to read a book if its raining and you don't want to hike. Although there are others that simply use bivies (might be another option for you) and deal with the lack of room fine.

I don't have any personal experience with the cheap pop up tents. I have seen some of them collapse in thunderstorms from a distance though. grin
On the other hand I'm sure some have used them and made them work.

Rockchuckler has a good list of some alternative gear to look at, (I hadn't head of bearpawwd before) but some of it, such as zpacks, is probably out of your price range. Both the six moon designs and bearpawwd shelters are very light and closer to your price range.

As far as REI, I like them quite a bit, but don't often shop there anymore because they don't tend to have what I personally want. Often you can find more innovative and lighter gear from cottage manufacturers like those rockchuckler suggested.