At least I'm set for about 8 years for this car, I've got 4 more 2870A that I got for under $4/ea on eBay, 3x 3600s I paid $7 for from Meijer, and an Amsoil 3614 equivalent that I got from a Habitat store for $2, I almost bought a 3600 equivalent from that store today for $2 but the filter wasn't still sealed in shrink wrap like the one I bought before and it looked a little dirtyon top to me. I've had mixed success buying from eBay, I got some 9018 cartridges real cheap they arrived in good shape, the 2870A, I bought 6 but I got a refund on one because it was dented (I cut it open and posted it here,) I had a bunch of 9837s I had to send back because they had clearly been stored in a moist environment, a lot of them had rust and some of the boxes looked to have rodent chew.