Sad truth is that the bulk filter places online have raised the significant savings to not the case qty, but the PALLET qty. Unless you are into the $2000+ range on an order there is no significant saving that isn't eaten up by the shipping cost.
Case in point, 12 WIX 57060 (for my caliber) 6 51503 (Senior filters) and 6 51100 (Junior filters) would save me $25 vs buying locally once shipping was applied. The local NAPA generally gives me the shop discount (10-15% off retail) if I pay cash. Previously there was either free shipping on case QTY, or the online prices were 40-50% of retail. Best discount I could get was 20% off unless I bought $120-$250 in a single filter, and STILL have to pay shipping

Bottom line... if you get a good price jump on them! And don't forget to share where you got them from.