Agree with the idea of an 'experience' rather than an actual gift. Holiday, concert etc..
My husband really likes sharks so for his last birthday I bought him a shark scuba dive at the aquarium (the only real shark diving one can do in Melbourne ). He enjoyed it a lot. If we had more money, I'd buy a holiday to some place where he could swim with sharks in the ocean (e.g. WA).
Anyway, try to think of something your dad likes then find an 'experience' to match.
Bought my Dad a hot air balloon ride for his 60th. Bets to do it with someone else so buy one for yourself and go with him, he'll love it (as long as he's not scared of heights, in which case he'll hate it...).
Like the Photobook idea and easily done these days- can do via Apple for less than $50
Second the experiences idea- chipped in with the siblings and got my dad a flight centre voucher and tix to the tennis open in Melb Jan for his 70th recently- he loved it.
Also consider a magazine or newspaper subscription if he's into reading.