Jesus man. You can buy as many Vanilla cards as you want at Office Depot. That has nothing to do with the bluebird. And you're essentially getting 500 points (assuming your credit card is 1:1) for that $4. If you do the Chase Ink deal, it's even sweeter as you're getting 5:1.
edit: If your card also has a minimum spending limit, you're likely getting even more for that $4. There are regularly cards that will give you up to 75,000 points if you spend $5,000 in the first 3 months. My quick math says that will cost you $40. The reward is best if you redeem for flights, but depending on the program that 75,00 points is still easily $500 in gift cards.
Its not a vanilla card limit if this lady isnt lying. You can only put 1000 a day, and 5000 a month on the bluebird.