You shouldn't be calling prices from the API on every single pageload that displays prices.
And it doesn't work like that, it's not a "first time" thing - its every page load, because every single time you load a page that calls the prices, you're calling the API. It doesn't cache those unless you set it up to do so.
I do understand that you're trying to be fancy and all, but how much time do you really save by having the pricing automatically updated on your website?