You may want to ask this question of Professor Casey who is a professional philosopher.
Just some thoughts from a someone (me) who is not an economist or a philosopher:
1. I think it is wrong-headed to think that a priori knowledge is “unrelated to experience”. Rather, you should consider a priori knowledge as that which is independent of experience. That is, such knowledge does not depend for its own verification on any particular observations.
2. Mathematical truths fit this category. The fact that it is always the case that 2 + 2 = 4 in base 10 mathematics is not something we conclude after a long string of observations in which we never catch those quantities behaving otherwise.
3. All logical deductions from true premises are known <i>a priori</i>. That is, the rules of inference guarantee the truth of a properly deduced conclusion, which is thus true independent of experiential verification or falsification.
4. Many people would argue that ethical judgments are known <i>a priori</i>.