Logic For Bid System Similar To Basic Adwords

[brentman]

I want to build a advertising bid system like adwords but a much more bare bones version for people to bid on leads. I have an enormous amount of leads so this would help me monetize them.

 

I have my database where I am adding new leads regularly like so:

 

ID, email, phone, sex, interests, opt in date, opt in ip

 

But now I want to build an advertising website where each person can sign up, log in etc etc. Thats all easy enough.

 

I am so lost on how to do the logic for lead selection!!!

 

I want each advertiser to select category and set a bid amount like $1 or $0.75 etc with their budget. Then it selects the highest bid with still available budget, adds the lead info to their account. But then I don't want the leads to be exclusive but I don't want to continually have it choose old leads or only fresh leads so advertisers get an average quality across all leads.

 

This is like blowing my mind complicated for me.

 

I know php moderately well and am extremely good at following directions once something is planned out and looking up particular commands if I get stuck, so no problem going point by point through a build. Just don't know how to plan this.

 

Please help! Where to start?