Ajax Forms with domainname check, price calculation and log.

I am currently redesigning one of our company hosting websites, however we are looking for a clean and simple Ajax order form with whois (to check if a domainname is available). And more importantly a price calculation (during ordering and in the end). And features order logging to a database and the possibility to add coupon discount codes (for hosting packages). We already searched on Google for such a PHP / Ajax form, though there enough forms, but none of them contain a domainname check and the price quotation. The only solution we noticed is WHMCS, however their pricing is pretty steep for a simple webhosting company. Also WHMCS has a lot of functions which we are not going to use, for example; support center (we use our own), billing system (we use our own), webserver account creation on-the-fly (we are not using this). So you are paying for a lot of options which aren't going to be used. An excellent example of how the form would have to work and look like is here: [login to view URL] When you click on Hosting Package > Advanced Package > Fill in a domainname > etc.... You will see how it acts and works. This is what I want and need. If needed I can supply the files which are linked to the WHMCS order form, which is open source according to their website. If the solution is getting to expensive we will have to go for WHMCS, but we rather have something simpler (and end up paying less).