Guys are in love with gadgets. An iphone or DSLR will be a great option if you can spend that much. Else go for JBL bluetooth speaker or Skullcandy headphones. Yup a guitar might also work if he's into it.
An Expensive Watch
An expensive and a classy watch looks great on every guy’s wrist. You can go for a sporty Fastrack watch, or a bold look Casio, Rado gives an elegant look. It totally depends on is his taste.
Some Travel Accessory
For traveler guy you will get many options in Decathlon, Travelpro or at last Amazon. Go for a rucksack/duffle bag or some traveling gadget which you feel will help him in his trips. If he loves photography then go for a DSLR go for a DSLR lens.
A Dinner Date
Take him to his favorite restaurant for the dinner. Plan a night out and watch his favourite movie with popcorn or cook his favorite food.
A Bottle Of Wine
Bottle of wine will work great for guy. If you still have doubt on this go for a nice & fine whisky like Jack Daniels, this will make sooo happy.
If you really know his style well. You could buy a nice shirt or Tee for him. A nice pair of shoes or Ray Ban glasses might also impress him.
An Expensive Perfume
An expensive cologne with masculine fragrance or something with sporty fragrance. You can go for a pack of perfume with hair moisturizer and body lotion.
Ticket To A Sports Event
Buy him ticket of his favorite adventure sport whether it’s paragliding, bungee jumping or a river-rafting. Buy him his favorite sport's tickets and watch the game together.
Makeover Of His Room
It’s not so popular idea but it works well as it is the best way to show your love and care. Give a complete makeover to your guy’s room; starting with bedsheet, get some nice cushions, wall stickers and rearrange it really well.