4 zuzim = 1 sela = 2 goats?

chad gadya, chad gadya,
dizabin abah bitrei zuzei

חַד גַּדְיָא, חַד גַּדְיָא
דְּזַבִּין אַבָּא בִּתְרֵי זוּזֵי

one little goat, one little goat
which my father bought for two zuzim

in the eretz israel museum, in the coin pavilion, you can see 4 actual zuzim, which once equaled 1 sela, with which, depending on inflation, you might be able to buy a couple goats...