Recently I've seen a lot of small handheld radios being advertised towards preppers and they're being reviewed by outdoor sites. There are a few things you should know about these cheap low power handheld radios.
1. Advertised range is a bunch of junk. Sure, maybe on a featureless wide open dried lake bed, you will get 26 miles from handheld to handheld. Much of the U.S. is not like that and you'll never achieve the advertised range in real world conditions.
2. Effective Radiated Power (ERP) is what really matters. Transmitter wattage is nice to know, but, what really matters is ERP. A 5 watt radio with a poor antenna could have an ERP of just 100mw. Likewise with the right antenna, a 5 watt radio can have an ERP of 60 watts or more. Also, while we're talking about ERP, we should talk about antenna gain. Antennas on these small radios are both zero gain and fixed. Just as an antenna will make a transmitter perform better, a high gain directional antenna will make a receiver perform better.
Now, I live in the Northeast U.S, and I've been an active ham radio operator (Extra Class) for 21 years. In those 21 years I've learned a few things about radios. Small .5 watt handheld radios are really only usable over about .5 - .8 miles. They work well in an area about the size of Epcot World or a campground and not much else. Using a handheld radio inside a car will greatly reduce the range of the radios to just a few hundred yards. You want the antenna outside of the vehicle and as high as possible. Right in the center of your vehicle roof is the best place. Even a 5 watt mobile radio is only good for 3-4 mile radius.
Now, there are things you can do that will assist with transmit and receive. Elevation is always your friend with RF. If you're on the open plains your effective range will be line of sight, and these radios will perform better in places like that. If you buy a radio with a detachable antenna, you want the highest gain antenna you can use. When you're mobile, a 3db gain antenna is about the best you'll get for vhf/uhf radios. At home, it's pretty easy to get an inexpensive 11db vertical (5watts at 11dbi = 39watts ERP)
If you want to buy radios for prepping, get the MURS band radios. Per FCC rules, MURS radios are able to accept detachable antennas (FRS is not), you don't need a license to operate the radios, and the transmitters are a healthy 2 watts (FRS is just 1/2 watt). MURS is all around a better deal if you want radios for prepping. Best of all, there are few people using MURS, so, when you need the radios the most the frequencies won't be clogged.