Amazon Prime --- Worth It?

Regarding "free shipping" the merchants have employed a new backdoor technique to increase prices. It works like this: There is a small electronics item I occasionally buy. It used to cost around $3.00 and the shipping was a little over $4.00, however, I could order four or five of them before the shipping increased to the next level, usually a dollar or so (combined shipping). Assuming I ordered five items at $3.00 and shipping at $4.00, the order total would be $19.00. Now the item has "free shipping," but the price has increased to $7.00, so now there is no combined shipping and the order total is $35.00! In other words, you pay individual shipping charges on each item, but it costs the seller no more to ship than before.