While we prefer and recommend manual 4 piece grinders, electric weed grinders are pretty neat. However, keep in mind that these grinders should be considered more of a novelty item than anything. They break easily, batteries die and you can accidentally over-grind your buds turning them into dust.
Head shops generally charge $29.99 and up for electric weed grinders. Given their short lifespan, we recommend getting the best deal on ebay. Check out the grinders below and let us know if you have better luck with them than we did.