Sorry, but you cannot spend someone else’ money. A set of Shas is VERY expensive and some in-laws just cannot afford it.
Regarding engagement rings, often the stone is CZ, for those parents who cannot afford the real thing, OR often, the stone (from the girls or guys family) is passed down and reset, again because diamonds are very very expensive.
It is important to have NO expectations regarding gifts. You are owed nothing beside love & respect.