In addition to the historical significance, buying legal antiquities is also a great investment. The price of antiquities increases over time because of the limited supply. Although condition plays an enormous role in the value of a piece, there are set prices for most antiquities, and they continue to rise over time.
For example, a bronze 25mm diameter Simon Bar Kochba (132-135 A.D.) coin in very fine condition was valued at $250-$270 in 2000 at an Israel Antiquities Authority licensed auction, and in 2014, the same coin was valued at $550-$580.
Another example is a Roman glass cosmetics bottle as shown below. There is a very limited supply of legal antiquities, so their value continues to rise. This makes buying antiquities a great investment.