You're probably doing a bad job of inviting people to share their actual opinions with you. The easy & practical choices here are:

1) People with more money to spend get first pick of stuff.

2) Lottery / people who get to the store-front first.

Both of those are legitimate, although #1 does have a lot of support and theoretical backing in practice. Most of the third ways that get tried devolve back into one of those 2.