We will spend lots of money buying books(改为被动语态）

Lots of money will be spent on buying books.
另外一种
Books will be bought by(这个是手段) spending lots of money by（这个by才是说谁作了这个动作，不要混） us.

Lots of money will be spent on buying books

Lots of money will be spent by us for buying books.

Lots of money will been spend on buying books

Lots of money will be spent for us to buy books.