I am interested in knowing the appropriate amount for a father to spend on his daughter's college graduation present.

A nice dinner to a new Vet,

Appropriate is only a reference to your income and situation,

You could give her a house in the country, a new car and a job at your law firm if you are an attorney.

If you work at the factory and are deep in debt, you may take her to dinner and just let her know you are proud of her

Paying for her college tuition is always a nice gift.

But I agree with Fr Chuck. Give her a gift that is WITHIN your means.