you should be able to use the aamc ones right away
gold standard ones are decent to supplement...$150 for 10 tests or $25 each...depending on how many tests you really want to take and how much time you have ..
theres also free gold standard one and a free princeton review one too if you want to do those instead of buying more..
i think a lot of people also do the Berkeley Review full lengths and Examkrackers..there are a bunch of threads on full-length advice though if you look 🙂