A largish number of Wizards of the Coast's D&D novels are priced at $2.99 at Amazon right now. Here's the search
I used, sorted by price, though you'll probably do better searching on a particular interest. Plenty of Forgotten Realms and Dragonlance among them, although I think their most popular series (Dragonlance Chronicles, say) are not reduced.
I spot-checked a few titles at BN and Kobo without finding any reduced prices.