The cost on this collection is so high - especially for pastors of small churches like me. Why not rent this out?

According to my pricing, it's cheaper to buy the volumes separately than bundled. I can get vols. 1&2 for $9.23, and vols. 3&4 for $9.23. Why would I buy the bundle for $24.99 when I can buy all four volumes at $18.46? FL needs to adjust bundle prices to reflect lower individual prices so that the price is consistent.