The outlay varies enormously depending on what you choose, can be under £60 if you go for traditional terry squares, or more like £150 if you go for a more modern shaped nappy system.
If you're not bothered about folding them, terry squares are very versatile, and by far the cheapest birth to potty nappy you'll find, plus they dry pretty fast too. If you don't fancy the folding, then I'd look at a shaped cotton nappy. A birth to potty nappy like Mother-ease One Size, or perhaps one that comes in 2 sizes, like Nature Babies Diddy Diapers. The plus of a one size is you only have to buy one set of nappies and generally it works out cheaper, but the downside is you often have quite a bulky nappy at first. The plus of a 2 size system is you get a neater fit especially at the first stage, the downside is you pay more overall. But you can sell on your first size nappies when you're done (or use them on the next one).
If it's your last baby, look out for some second hand nappies, a cheaper way to get started and find out which you like. Or find out about a nappy trial scheme that lets you borrow some nappies, "try before you buy" kind of thing - this is not the same as the "trial sets" that some nappy sellers stock, which would more accurately be called "starter sets" as you can't usually return them once you've tried them!
Dirty nappies are easy to deal with, use a flushable liner and put the lot down the toilet. Once baby is doing more solid poos, you could then move to fleece liners and plop the poo down the toilet and wash the liner with the nappies.
I hope that helps
Christine