DHCart v3.79 owned license fee is just $19.95

DHCart is a PHP based application that provides a simple to use shopping cart for users purchasing domain names and hosting services.

DHCart has been designed to be easy for your clients to use. Selecting domains, verifying availability, adding hosting and the shopping cart are all controlled from one page.

DHCart can be used simply to sell domain names or can be enabled to offer hosting packages and domain transfers as well.

Uses PHP available on most Unix and Windows servers.
Works with over 400 domain extensions.
Determines domain availability.
Any registration periods and prices allowed for each domain extension.
Option to select hosting package for each domain name(if you enable it).
Providing free domain with hosting or selecting a hosting can be necessary(if you enable them).
Supports domain transfers(if you enable it).
Easy to add to your own page layout * even inside a table cell. Also it use CSS file. All of the colors and the fonts can be changed by editing the CSS file.
Easy to include only the domain extensions you wish to sell and support.
Built in support for 2checkout, Paypal, Moneybookers, Nochex, E-Gold and manual processing. It can be integrate to any payment gateway that other than these, too.
Supports monthly recurring billing on Paypal.
Sends email to customer and vendor with order details at checkout(supports SMTP authentication).
Supports Tax.
Supports any currency symbol and/or currency name.
You can set the currency exchange rates for each payment gateways if your default currency is different from them.
Uses language file for easy translation.
User defined fields for order form.
User defined email messages.
It includes a simple coupon system. You can offer one time or recurring discount on hostings or domains.
Excellent documentation.
And more...

Demo: http://www.dhcart.com/demo/order.php

Buy: http://www.dhcart.com/purchase.php