The constraint is arithmetic
A €20 product at 35% margin has €7 to buy an order. In most niches that is one or two clicks. No bidding strategy changes it.
So the work is AOV
- Bundles priced so the bundle is obviously the better buy.
- Free shipping thresholds set just above current average order.
- Post-purchase upsells — and pass the value back, or your best orders look average to the bidding.
Big catalogues, thin data
Hundreds of low-volume products means most have no meaningful conversion history. Group by margin tier rather than trying to bid per product.