If you only want to purchase the "I" here is the link. It sales for $ 1.00 but I believe a $ 5.00 minimum purchase might be required.
Try cutealphant.com for the frog alphant you might find it there.
It's on page 2 here in Alphabets. Here's a direct link to the pack. You could buy just the "I" but your minimum order should be $5. Or for the price of two alphabets you can buy a membership and download everything on the site, included what is posted in the next 6 months.