[TheBang]

We can't condone pirating of any officially released material here, like B-sides. Currently, your best bet for obtaining those legally is the super deluxe box set versions of Dubnobass and Second Toughest (or the equivalent digital versions). The box sets recently dropped in price at Amazon and other retailers, so it might be a good time to pick them up. Also, the Anthologies.

Unfortunately, for later B-sides and remixes, everything is out of print currently. You can either wait until the planned box sets for those albums are released, or you can buy the singles and EP's on the secondary market. They're readily available there, and most are pretty cheap. You can try eBay or discogs.com or marketplaces like musicstack.com for those.