I think its just good business by Steve, in my case I would not of bought one of Steves books for $2.50... I havent heard of him and I cant pick up his book in a shop and read the first chapter so he loses those sort of sales that would normally get me 'into' an author.
Steve then gets $0 from me..
This way I hear about the offer.... figure that '10 books for 10 bucks'(great line you should use this

) is a great deal I bought them.
Steve gets $10 from me...
AND if I like them I will happily then pay $2.50 for a new book.
Steve then increases sales of his new book.