The gift of "time." Arrange to spend "specific" time for just the two of you, be it lunch, a museum, a park etc. present him with a personally written card with memories the two of you share. It's a no-miss gift that your dad will never forget!
63, up to about $75, hobbies include bird watching, ranting at the television (he's a Fox News fan), reading, the Astros (we're taking him to a game on Friday), hunting (he's got a trip lined up), road trips which he begrudgingly does but secretly loves them (we're going in October), ...if I think of any more I'll add to the list.
Last year, I got my dad a really nice squirrel proof bird feeder and some nice food for it. He loves it. This year I am getting him binoculars so he can watch the birds. For Christmas I gave him a little lens kit that attaches to his iphone and lets him take closeups.
Maybe if you talk to the matron ( be it Mom and/or eldest sister, etc) of the family and openly explain that "that" is your personal desire for your Dad this year, they will understand. People, especially family can surprise you sometimes! Good luck!
My Dad is difficult to buy for as well. I bought a frame with different sized openings (a few 3x5 landscape some 4x6 portrait)I think it had opening for 8 pix and I put family photos in it for him. Now every year I give him new, updated pix to put in. He appreciated the effort and thought put into it.
OK so...I got him 2 DVD's - Beautiful Planet's Italy and France (He's been to both, LOVES them, and is such a huge nerd he'd love the film) and Apollo 13, which he was lamenting the fact that he only had it on VHS the other day and the cassette player eats videos these days. I was going to get him the 25th Anniversary presentation of The Phantom Of The Opera, but he bought it for himself, the goob. I also got him a stainless steel grill top to his veggies don't fall through the grate, and a pack of flashlights because his always seem to go missing. Also two cat cards, cause he's a cat nerd. He talks to them more than us sometimes, lol. I'm pretty happy. I'm gonna divvy it up and let my kids give him some of it. :)
For $100 you can get his name and short inscription put on a brick in front of Minute Maid Park. I did that for my husband and boys---they loved it!! They visit their brick every time they go to an Astro's game. The info is on the Astro's website.