On the US Steam store, checked 12 September 2026: the base game is $39.99 [S1], the Supporter Edition (game plus Supporter Pack) is $49.99 [S1], and the Supporter Pack DLC on its own is $12.99 [S1].
The Supporter Pack is cosmetic only: three starter weapon camos (Valkyra A-91, Lonestar Bushmaster, Manticore KH-2002), a Little Bird "Taxi" camo, a supporter icon on the scoreboard that you can hide, and grenade and helmet bobbleheads.
Buy the base game unless you want to back the studio. Nothing in the pack affects cash, XP or combat.