Nothing.
Most N64 games I want to play were remade in far better form on later devices where they are still playable, unlike the N64.
Emulation improvements take care of the rest.
I've always wanted an N64 for a few games. I didn't have one at the time as i got a playstation instead ( still dont regret it at all ) as @FAST6191 said most of the games were remade or i've played them though emulation, but that i wouldn't still buy one today. I genuinely feel like the games for the N64 were designed around the controller and one day i probably will get one when i see one for the right price.
CEX is ALWAYS over priced tho £35 for a used PSC ? Pfff i got mine £20 brand new from amazon a while back