this is what I use when spray painting and some of the nastier demo we do.
if you shop, you can find the mask with cartridges for around $75 or less
replacement cartridges can be found for $12 bukz a pair on fleabay.
I get mine from Sherwin Williams (my SW rep gives me the $12/pair pricing)
Buy peel off face shield liners too ..if you shop, you can them for about 50 cents ea in bulk
or just go the Harbor Freight with a 20% discount coupon and buy the one that's on sale
..L.T.A.