I've been looking at these type of ACs too because my windows do not open vertically but are cranked outward.
I asked around alot and found out if the portable AC does not get vented out the window (which I cannot do), there are some that do not require any kind of venting whatsoever. The problem is, the advertised BTU goes down significantly if it is not vented externally.
I saw a Haier at BB for about $450 which was advertised at 9000 BTU. Without venting, it is only 5000 BTU.
If you are buying one of these and don't plan on venting outside, you should ask them what the BTU is without venting.