There are so many nice items (not only books) with spells on them. But they are not used very often and not sold even for the lowest prices.
Why not change the way they work and make them use the caster level of the one who uses them?
Maybe also take UMD ranks (e.g. rank/2) into account.
That way burning hands or melfs arrow, web, ghouls touch and many other things would get somewhat useful.
And it would help normal casters with limited spells. (1,95% normal sorcerers and 6,32% wizzards isn't too much)