163 forsure. 170 cm is like 12 cm taller than you which would be 100% overkill for a park ski even if you are hitting 60-80 foot booters or unless you weigh 200 lbs.  it will be a lot easier to progress and stuff on shorter skis cause they are easier to throw around. Honestly park skis should be within 5 cm of your height on either side unless you are exceptionally light or heavy.
As far as inexpensive recommendations line tigersnakes are both pretty soft and pretty cheap but they are a more entry level park ski. Chronics are another good option little beefier and a bit higher quality while still being within a reasonable price. Those are just the first to that come to mind.