Define "Conversion Rate":
(a) Percentage of random visitors who place an order: 1% might be generous.
(b) Percentage of targeted visitors (via ads or product feeds) who place an order in the same visit: From our data, it's 3 - 5%.
(c) Percentage of targeted visitors (via ads or product feeds) who *eventually* place an order (possibly on another day): Tough to measure, but I'd guess 5 - 10%.
(d) Percentage of visitors who add something to their shopping cart, and eventually complete checkout: 30 - 40%. (60 - 70% of carts expire with goods in them).