Adorama has several Manfrotto circular ND and polarizing filters on clearance.
The 3 stop ND filters are $9.99 – $19.99 and the 9 stop ND filters are $19.99.
52mm 3 stop $9.99
58mm 3 stop $9.99
62mm 3 stop $19.99
72mm 3 stop $19.99
72mm 6 stop $24.95
82mm 6 stop $19.99
All available 9 stop are $19.99.
https://www.adorama.com/bgmfnd50058.htm