There are some very good deals to be had in some of the bundles when combined with the 25% rewards. The rewards are based on the suggested retail price, not the BoB discounted price. Some of the Kensington bundles are already marked down 50% (even more if you factor in the per book price before bundling).
Here are a few of the best combined discounts I've seen:
Cynthia Eden Eternal Flame Bundle - 3 books for $14.98 (Rewards $7.25)
[$6.89 - $7.32 when bought separately on Kindle]
Maggie Robinson bundle - 3 books for $14.98 (Rewards $7.50)
[$6.89 - $7.32 when bought separately on Kindle]
Donna Kauffman bundle - 3 books for $14.98 (Rewards $7.50)
[$6.89 - $8.09 when bought separately on Kindle]
Shannon McKenna bundle - 5 books for $14.98 (Rewards $6.50)
[$4.30 - $4.89 when bought separately on Kindle]
Lisa Jackson bundle - 6 books for $19.98 (Rewards $8.25)
[$4.30 - $4.92 when bought separately on Kindle]
Sally MacKenzie bundle - 7 books for $19.98 (Rewards $8.50)
[$2.99 - $4.47 when bought separately on Kindle]
Many other
bundles available from Kensington, Sourcebooks and Harlequin