I don't get how these can be fun.
You spend 10 seconds shooting them at each other for every 5 minutes spent walking around finding and reloading darts.
That sucks ass.
Save the money for paintball guns.
Because they're extremely inexpensive (NERF guns range from $5-$60 max), but are still fun to play with, can be used inside a home, the ammo doesn't become unusable after one shot, so you don't need to keep buying tanks of it, and it doesn't hurt to get shot, so it can be played with absolutely anyone. Plus, modding them is really neat, I modded both my Maverick and my Longstrike. They're not an alternative to paintball/airsoft, they're just some good fun. They're not really comparable.
Plus, the dart-finding is trivial unless you're obese, it's just part of the game and it's not that difficult.