I've managed to not buy a single sposie for DD (though we have been given a bunch here and there, no whole packs of anything) and have been using a combination of flannel flats (till last week), terry flats (on the weekend started those), pocket nappies and elimination communication. DD is 4 months old and we're not using night nappies at all - easy on the washing duties!!
So, I hear you on the pain associated with the thought of buying sposies.
Here's some encouragement - EC is a matter of persevering through missed signs and wet legs (mine!) and I've just been bloody minded about it, reminding myself of the long-term goal. With DS teh long term goal was to have a heavily reduced carbon footprint by using cloths (used sposies overnight for a long time till I reverted to pockets for a short time before deciding to try out some EC principles for night continence - that gave me the confidence to do EC from early with DD!!).
Anyhow, for the nappy rash make sure it's not thrush. Whether it's thrush or not, get some nappy free time in for the bottom's sake.
HTH