Ace hardware has Ace Basic Pleated Furnace Air Filter
BUY TWO GET ONE FREE ($4.99 each or 3 for 9.98 )
Valid Dec 26 – Jan 31
I got MERV 8 rated 16x25x1 filter from my local store (3 for $9.98). They had plenty in stock for different sizes.
Link for reference only
Credit goes to @TAZ11