Snowbee, yes they are cost effective.
Basically you have two choices, you can either buy 2nd hand cloth cheap (or buy cheaper brands new like prefolds and wraps, Mio Solos are often on offer and shops like Aldi and boots usually stock them) OR you can buy the more expensive ones like Tots bots Easyfits, Wonderoos etc and then sell them on when you have done which will recoup some of your money
I use cloth, I used them for my 2nd child and my 3rd (current) baby. But I bought a lot of them 2nd hand with my older daughter because I didn't want to spend a lot and not get on with them. When she toilet trained I kept them but after a few years I either sold or sent to charity the older 2nd hand ones and just kept a few 'favourites' and brand-new-to-us ones.
I had a big gap and my older daughter was (is) 9 when my baby was born so I've had to buy a lot of cloth nappies anyway. I bought Teenyfits brand new which I am now going to sell, and I bought some 2nd hand tiny fitted nappies as well because when my baby was newborn even the teenyfits were too big around the legs lol. Anyway, I'm selling on all my first size newborn cloth as they are in good condition. I've bought a few new 2 part size 1s and a load of 2nd hand size 1 2-part nappies and a few new wraps for over the winter (as the nappies can be tumbled to speed up drying time), When she's out grown them I'll sell most of them on again for similar to what I paid (about £1 to £2 a nappy).
Then I have tots bots and wonderoos which will last til she potty trains. Some I bought new, some second hand but all in good condition so will be sold on once she trains. And then I have a few that I kept from last time.
I would like another baby but I'm single so it might not happen and I don't have the space to store loads of nappies so I think I'll sell them as the money would be useful. If I have another baby in a few years I'll buy more then lol.