Price display is a function of CSS for list building and/or product landing page.
You should see prices on the checkout page.
As far as the purchase options, once you have downloaded/installed the payment plugin you wish to use, just paste the shortcode into the HTML template. You can see an example here;
Then, you will see a link to license/pay for the plugin, once paid the payment functionality appears on the checkout page.
For reference here is the general process to setup a store:
And since you're developing sites, consider using the website development framework that we now make available to the community;
It's great to build sites with SeoToaster.