For a limited time but some nice useable snippets in these packs.
Mine are free most of the time (33 packs and counting), although I’m not going to spam that link
MusicRadar’s constantly-free ones are pretty good, depending on what you’re in the market for. They really shine with field recordings and drum breaks, but ymmv depending on what you’re looking for.
Also I should mention that bandcamp can be a bit of a goldmine for free sample packs. It definitely takes some digging around but it’s totally worth it, because people are always tossing up cool field recordings and random stuff.