IMS Pavoni Lever 20g Precision Filter Basket ø 51mm - PA2TH29E From  $52.02

Being the same diameter as the Delonghi Dedica stock basket but not pressurised and also much better quality then most aftermarket baskets I am very happy with my purchase. Truth be told, I had to carefully flatten the collar a bit with a wise to achieve perfect fit but was worth the trouble.
Not my first purchase from The Espresso Shop as their selection is extensive, prices are reasonable and shipping is fast. I can recommend both the shop and the product.

Flattened the lip to fit a DeLonghi ecp31, does the trick and can fit quite a bit.