Here is a free mod to use for now. At least this will give you a trial run on how your system will work.
https://vborg.vbsupport.ru/showthrea...hlight=raffles
As BirdOPrey5 said, you will have a hard time coming up on top. You will need to sell items on your site to help cover the cost of product discounts and so forth.
You will have to do a little code changing, but it's a raffle system, but you could add DBTech vBActivity and Awards
https://vborg.vbsupport.ru/showthrea...ghlight=dbtech