that budget. Obviously, there are much higher quality guitars, but with that budget you’ll be just fine.
As you can see, the internet is replete with advice, even to the extent that it’s overwhelming. I won’t give any advice on guitar types bc it’s like shopping for a car—a lot are good and will make you happy, just go find the one you like.
I’ll echo the importance of getting the guitar “set up” first, like a few others already have. Should be less than $100 and they’ll make sure the action isn’t too high (meaning how far the strings are from neck), minor adjustments to the neck for better tuning, and they’ll make sure the frets (the little metal thin bars on the neck) are filed down and won’t catch your fingers. If you’re buying it new they should give you a good deal on the price. A nice guitar that isn’t setup will make for a bad experience, and likely won’t sound as good anyway. It really does make a big difference.
Don’t hesitate to talk to the guys at the guitar shop, if that’s what you do. They’re not like used car salesmen. They love guitars and love sharing what they know and helping you find what you want. They can sell you any kind of guitar they have so they’re usually happy to make sure it’s the right one.
One more thing: if it doesn’t have to be a surprise, having your son there to pick it out is a pretty great experience. It’ll be a core memory for him. Everyone that plays remembers their first guitar and how they got it. Everyone.
Good luck and Merry Christmas!