Don't buy military climbing gear!! That stuff is total crap: heavy, outdated, and not built for high performance. Buy a proper civilian harness, rope, belay device, carabiner, etc. from reputable UIAA certified civilian gear companies like Petzl, Black Diamond, etc. I guarantee special forces soldiers and advanced mountain brigades are either equipped with or purchase their own civilian climbing gear. But learn what you're doing first, rappelling is one of the top causes of climbing deaths.