Whats the cheapest calculator that can do calculus/graphs/solve equations/ matrices/determinants?

that can be used in an a-level exam in the uk. they say you can use graphics calculators so i take it that you can use graphics calculators that do anything. they dont check anyway. i want to get one that can graph functions, solve equations (differential eqns if possible) differentiate and integrate and use matrices and has plenty of stats functions