Yeah, the E-Reader+ Cards alone are worth the purchase of the Mega Man Zero Collection. I have seen several people complain that the extra features are not even worth it because they were in the Japanese version. Granted, the ability to use the Japanese E-Reader+ Cards were in the Japanese version of Mega Man Zero 3, but you had to purchase the cards first.
For example, the US never got the E-Reader+ because of the lack of success the E-Reader got, but when the E-Reader was the latest thing in the US, you had to purchase the cards. A E-Reader card for the Pokemon Ruby, Sapphire, and Emerald game currently costs up too $48 USD on Amazon. When they were current, I believe a pack of 5 for $9.99.
Looking up on websites like
http://www.toysnjoys.com you can find that you can purchase a pack of 5 cards for $3.95 USD + Shipping which comes too a grant total of $11.20. So you would have to spend roughly $200 USD to collect all 100 E-Reader+ cards, assuming that they go for the same price as the E-Reader cards.