Kathy Kieffer: That's tricky. I'd want to look this up in the dictionary to be sure.

Alicia Rosov: I had to look this one up! My gut was A, but I wasn't sure.

Rob Ault: AHIII says "collectable" is the variant.

Yocheved Golani: With the collector comic industry and awful typists in publication classified ad departments around the USA invading the grammar world, the second form has become the norm as far as I have observed.

Dennis McCarthy: . . . but I'm a bad speller.

Mark H. Bloom: Both are correct (per Webster's), but I prefer the second choice.

Carrie Garbas: I prefer "collectibles" with collectable, as an adjective. I do believe they're both correct as nouns, though.