When you creating new campaign - you can select from 2 budget types based on:

• total cost of campaign
• total count of offers

Bid - is your price for complete full one offer. Minimal - $0.05 for android installs. You can set bid value as you want, but remember bid value directly effects to:

• total installs count - than higher you bid, than more users will wants to make your offer
• install count per day - than higher you bid, than more users will wants to make your offer

Why need to pay more than minimal price per offer?

Cap - daily limit

Even on minimal bid - users can will want to make your offer more than you need it. Its usually happens when offer is simple (install + do not delete 3 days)

Other factors effects attract users to make your offer

• Bright, unique icon
• Higher position in searching keyword (for campaigns with installs from search results)
• Small apk size
• How many days to not delete app - comfort value is 3 days
• Friendly, useful app or great looking or popular game
• Safe looks app page
• Clean and simple campaigns goals (reach hero level 5, complete 3 easy levels)