the only one I am familiar with is lasermax. About $300
i bought a P220 way back when and it came with one. It was fairly inaccurate.
Not my style either way, so I sold it on ebay for $250
I would just practice raising the gun up and finding the front site. F/O or Tritium helps a lot, I've got F/O on all my carry guns and house guns will eventually get Tritium
Please do yourself a huge favor and don't waste your money on it. There is only 1 manufacturer of them that I know of that was already mentioned. I learned the hard way TWICE. Such a cool gizmo if it would work
Unless some miracle in technology was developed; they just flat don't work with any consistency or maintain any accuracy you could bet your life on. Just a gimmick that seems like a cool idea, but consider this
1) you are replacing a pretty crucial part of your gun that was built, tested, and certified by the manufacturer for that gun, with one that is an unknown.
2) small delicate electronic parts won't stand up to the repeated pressures and forces generated against the guide rod for very long at all unless they contracted out the work to NASA then maybe. I think the reason they are still so expensive is they are getting the one and done sales vs repeat customers. Just a guess, maybe they work great now, but I doubt it. If I'm wrong then my apologies to that company