This happened to me as well. I broke off the end of the coil/spring while bending to make a “hook” shape.

I looked for purchasing just the spring, but could not find it. Next up was the entire cupholder apparatus, either used ($~26), URO ($~39), or OEM/genuine BMW ($60-75+). This isn’t cheap and is not actually necessary to buy anything ,though.

Much easier is what I did instead, which was taking advantage of the coil material’s rigid/”easily-snap-off-able” property to make a new (wider) hook. I pulled the snapped end of the coil out a little, then put in a thin screwdriver to kind of hold the coil out extended. Next I used flat nose pliers to hold the end flat, while using long nose pliers to break off a new gap on both sides, effectively making a new “t” end. Then of course I VERY GENTLY bent it around to make a “hook”. I gently clipped the new spring hook into the preexisting plastic hole. It works for new after reinstalling. We’ll see how it holds up!