It sounds like the Amare and Marion cards were solid finds. I had given up collecting during this time frame. Also I couldn't figure out which brands to buy and which were true rookie cards. Beckett used to print a card guide as to value but I gave up subscribing as most of my cards were worthless.
Too bad you do not have those early cards. They would probably be worth something today. Those were the days when they did not overproduce a card which lowered the value.
I still have a bunch of Shawn Kemp rookie cards that I thought were going to make me rich some day.