Buy event how to do it?

I am looking to make an event to buy certified crafter products in AH but need some help to make the rules
Looking to have some prizes, first is according to points accumulated and second i want it to be ramdon luck base so dont know how to do it or explain it well in english, so lucking for some suggestion to stablish rules
Each buy will give one point for the first prize, and one chance to second
Have a nice day

Player can buy only X amount of items every day. To avoid situation when one player just buy out everything. Also depends on the items - for weapons it could work.

Player who buy any item from that crafter can’t sell that item further - for example if player bought Herman Law-202(L) with full TT then he/she can’t put it back in auction with full TT (or at all).

About random second prize - each point guarantee one entry to the random draw for second prize. So if player earned 10 points - he have 10 entries to the draw, player with 1 point - only 1. So higher points will provide higher chance of winning second prize but it still wouldn’t be 100%.

You can also track players in order who bought first, second, etc. For example: 1.-A, 2.-B, 3.-C, 4.-A (A, B, C - players). And then just pick a random number and compare to the player list.

My aim is to have a watchlist products and other of certified crafters which will give points, was thinking of having to post 2 screenshots one open with crafter good window were we can see his name and in the background ramaining goods to check with next were it wont be the one at same time