The cost of acquiring a customer in e-commerce grew by almost a third over the past year. According to E-Promo Group (an analysis of more than 99,000 performance campaigns), CPA in e-commerce in Q4 2025 was 32.9% higher than a year earlier, and 9.7% higher than the previous quarter. The forecast for 2026: another 15-20% increase. Here's what's telling. Across all industries, average CPA growth in…