Hiya
It will depend on which type of nappy you want to use, The cheapest option is using prefold nappies along with wraps, the more expensive but easyer options are All in one/two nappies or pocket nappies, these are most like disposables.
How many nappies will depend on the age of your LO and how often you want to do a wash.
The following are handy things to have if using cloth:
A nappy bucket
Wet bags for out and about
Fleece Liners to protect your nappies
Flusable Liners, as above but you can flush them
Theres lots more experianced cloth bum mums on here that will be able to help more but thats a start x