Lol. $100 Galaxy MP5K....that's something that's worth some thought. Worst comes to worse, you can always upgrade it down the road when you get more money.
You should probably stay away from things like minis and electric pistols because they have extremely low power and aren't known for being the most reliable thing.
If you do decide to get an MP5, then you could get something like this:
which could be what you are looking for.....