There's no fixed price for Instagram Story ads. However, an average Instagram Story ad cost varies from $0.20 to $6.70, depending on the bidding model. There are three bidding models: CPC (cost-per-click), CPM (cost-per-impressions), and CPE (cost-per-engagement).
Most advertisers agree that they pay an average of $0.20 to $2 per click, $6.70 per 1000 impressions, and $0.01 to $0.05 per engagement.