Buying 2nd bike that's been garaged for a while

Mate is buying a 2nd hand BH Contour. Friend of a friend apparently, bought it, cycled it very sparsely and then put it in a garage where it's been for 'a couple of years'.

This is a bike in Brisbane Australia. It gets plenty hot and very humid in Summer and surprisingly cold in Winter. So, what degrades over time for an unused road bike? What will need to be checked/serviced? Tyres? Cables? Hubs? Chain?

I'm just trying to factor in any hidden costs for my mate because he's kinda skint at the moment and his last bike got written off when another cyclist swerved into him causing him to go into a pole..... And get this, once the offender saw the bike was ****ed he got up and cycled away as he knew my mate couldn't follow him..... classy hey....