Linear motors are almost as awesome as lasers. It's taken a while to harness their power, but we're starting to see them show up in stuff like electromagnetic aircraft catapults and even honest-to-goodness weaponized railguns. Both of these things are probably out of your budget, but you can build a small coilgun on your own without too much trouble. Let Mehdi Sadaghdar and his eyebrows show you how. Sort of.
And yes, we'll say it so that you don't have to post angry comments: this is a coilgun, not a railgun.
A railgun accelerates an object by pumping current up one conductive rail and down another with the projectile between them, passing current through the projectile itself. A coilgun, on the other hand, accelerates an object by pulling it through a series of magnetic field generating coils that turn on and off in sequence. Both work on the same general principle of using electric current to accelerate objects, and both can likely hurt you if you try to build them as, um, creatively as Mehdi does.