Vastly cheaper to postpone now just don't send junk up, but the problem is mostly limited to keeping satellites in space not simply leaving earth.
Even then in LEO you get enough drag to limit risks and the worst case ends up as a trade-off of safety vs continuous fuel usage. Remember, space is vast but satellites and space junk are both really fast and stay up for a long time. Prevent junk from staying in your orbit and the risks dramatically decrease even more so if you add maneuverability. Even better LEO prevents your satellite from adding to the mess long term.
Even then in LEO you get enough drag to limit risks and the worst case ends up as a trade-off of safety vs continuous fuel usage. Remember, space is vast but satellites and space junk are both really fast and stay up for a long time. Prevent junk from staying in your orbit and the risks dramatically decrease even more so if you add maneuverability. Even better LEO prevents your satellite from adding to the mess long term.