I wouldn't be surprised if Amazon does crazy stuff with cookies and individualizes prices, but I was browsing and looking to replace my lost CPL and stumbled on a good sale.
Tiffen 77mm UV filter reg $55.89 is $14.84
Tiffen 77mm circular polarizer reg $150.19 is on sale for $38
Other types and sizes are also at a similar discount.
This is a SCREAMING deal if you are looking for Tiffen filters.