I bought a box of 50 disposable masks as the price was so good at .32 cents a mask. Whick means it's probably cheaper to wear them then wash the washable masks. I haven't done the math but it seems like it could be true especially when even though they are disposable it doesn't mean you can't wear them more than once.
Actually for me it's the gloves that concern me most. I wear gloves because I think when you touch things like at the check-out counter with the ATM machine you might get something there.