175%
If you want to calculate the percentage increase in price, use the formula:
Percentage Increase = (New Price - Original Price) / Original Price x 100
In this case, the original price is $1 (the price of buying the cards) and the new price is $2.75 (the price of selling the cards). So, plugging these values into the formula:
Percentage Increase = (2.75 - 1) / 1 x 100 = 175%
The percentage increase in price is 175%.