If he doesn't have any lightsabers you should probably go with either the red Darth Vader lightsaber or the blue Luke Skywalker/Rey lightsaber. Those are safe choices unless you happen to know his favorite character. There are many choices these days with regard to various lightsabers for various characters.
I would say a nice lightsaber replica is an excellent gift for a Star Wars fan. I have 2 myself and I enjoy them very much. I usually take them out during Halloween to have fun with them.
For the price and quality you can't go wrong with the Hasbro Black Series Force FX lightsabers. Although for a similar price Disney has a "Deluxe" lightsaber line that may be of similar quality and price. The Disney Deluxe Lightsaber features a removable blade whereas the Hasbro Force FX lightsaber does not. I haven't handled the Disney lightsaber personally. Maybe you can see for yourself at your local Disney store in the mall. You might be able to see some of the Hasbro Force FX sabers at ThinkGeek or Gamestop so you can see what they are like.
Disney Deluxe Darth Vader Lightsaber
This deluxe Darth Vader Lightsaber, with its distinctive red blade, will tempt Star Wars fans over to the Dark Side. Finely detailed, this true-to-story replica is complemented by a wall mount and hilt stand for the ultimate in collectability!
www.shopdisney.com
Disney Deluxe Rey (aka Luke Skywalker) Lightsaber
A true-to-story replica of Rey's iconic blue lightsaber as featured in Star Wars: The Last Jedi. This authentically designed and detailed lightsaber is complemented by a wall mount and hilt stand for the ultimate in collectability.
www.shopdisney.com
Hasbro Force FX Rey(Luke Skywalker) lightsaber
Imagine the biggest battles and missions in the Star Wars saga with lightsabers from The Black Series! With exquisite features and decoration, this series embodies the quality and realism that Star Wars devotees love. Capture the power of the Jedi with the Rey (Jedi Training) Force FX Lightsaber...
hasbropulse.com
You can shop around and see what current lightsabers are available and their prices at places like Amazon, Gamestop, Best Buy, ThinkGeek, Disney Store, etc.