Pricing
Prices range from $49 to $279. From the reviews I've read they are all pretty much the same. High price won’t get you anything better.
How they Work
Most use frozen inserts or ice, or ice trays that slip into the unit. Then a fan blows the cool air out. So they are "not" mini air conditioners.
Do they work?
The independent reviews on YouTube are fairly bad. If you live in a humid environment they are worthless. One guy has 3 in his bathroom and it created a thick fog. If you live in a closet or studio apartment and have one close to your body they may help a little in non humid climates.
Summary
If you live in a humid climate or have a normal size living space - you are better off using traditional A/C.