There is a difference in offering incentives to join in and bribe members, although in reality this may be a very fine line.
I see the value of bidding competitions and other prize-based competitions as an incentive for members to join a (new) community. However, I have also seen that most members leave the community or become lurkers once the awards are given and the incentives are gone. If you manage to maintain the incentives for the long term, this could solve the problem. However, this requires a lot of money and investment that most people do not have (or would prefer to invest elsewhere in the location).
It's much better to advertise in an intentional way and find members who are interested in the community niche and its offerings. These are the people who will stay and be active contributors. Some of them may come from incentive-based competitions, but probably not very many and probably not enough to be worth the investment.