You sound like a very thoughtful DiL finnishline (my own buys lovely gifts).
Personally I love a good diary (Cath Kidston is my favourite) a pretty scarf, PJ's (BHs and M&S both have 20% off events at the moment) a bottle of nice fizz (if she drinks, or a posh cordial if she doesn't) something from Lush (I love the soaps and the bath bombs) a special packet of coffee, posh tea bags, body butter (can't beat body shop for the price) smelly candles, cosy socks, a nice fleecy throw (bhs again excellent value), a Cd compilation, a good biography, pretty little earrings, a box of Florentines (M&S are my fablvourite and a real Christmas treat for me at around £3 ) .... All within your budget I think.
Good luck.