"...expensive tomes..."
For me, that's anything that costs more than $0.99 + $6.49 Shipping (Canadian dollars). Problem is, I've already bought all the $0.99 used books that I want (my Jeremy CLarkson collection, LOL!!). I've been forced up-market, purchasing more expensive books that are sometimes even over $10.
On the other hand, I do have a few $100 price class books. Six of them are signed by people that have wandered around on the Moon. :-)