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Wow, some heavy misunderstanding happening on this thread.
Lets clear a few things up:
More power = more range? A bit, but not much. In simplified terms, doubling your output power will roughly increase your range by 1/2 (the actual amount is something like 1.4xx times, so just under 1/2). And by range we're talking about clear, line-of-sight range (like on open water or mountaintop to mountaintop): people, trees, buildings and terrain will diminish that range, usually quite considerably.
In this case, going from 5W to 7W is less than HALF double, so the actual increase in range would be under 1/4.
Watts play only a very small role in broadcast range. What it WILL do, as Deadpool pointed out, is it will spill over on adjacent frequencies. We're usually broadcasting on FRS frequencies which are spaced with 0.5W power in mind (2W or upto 5W for GMRS channels). Broadcasting with more power just means people on other channels will hear the transmission too and you might end up drowning out transmissions from people elsewhere (which you may not hear because they arent broadcasting with as much power) -- in effect you'll be inadvertently "jamming" your team's comms.
Your antenna plays a much more significant role in increasing your range: an antenna with increased gain for example. 3dB gain will increase your range by 1/2 (1.5x) -- doubling your output power is also a 3dB increase. Think of an antenna with no gain (called a Unity antenna) as broadcasting a signal you can visualize as a sphere: it broadcasts as far "up" vertically as it does horizontally (distance). Antenna gain "squashes" the sphere, at 3dB the sphere will be half as high but twice as wide (diameter, therefor the radius is 50% longer thus 1.5x range increase). At 6dB the sphere is squashed even thinner but is four times as wide (so radius is doubled).
The problem is with enough gain the "sphere" becomes almost flat and the radio antenna becomes directional. This is fine if you have two aligned antennas, on a building for example such as high gain wifi relay antennas, but in practice it means you'd have to tilt your antenna up towards someone who was above you (on a hill for example) even if they were close by (think of a narrow beam flashlight).
The second factor to increasing range is getting the antenna away from the ground. People shove their radios in their vest pouches or on their belt, etc where their body soaks up a portion of the signal. Trees and vegetation, other people, the terrain, etc all contribute to lowering signal strength. Getting a longer antenna (higher gain antenna usually are) will also help with improving comms.
Point in case, $50 is a good deal for a radio. But don't get it just because its 7W, because the increased power by itself won't help you much.
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