What a second guys. This is a great idea, in theory, but... please take a step back and think about this a bit.
In our experience, we've found it is better (more completed sales) to initially sell the customer on the most basic services and just get them signed up. Presenting them with various "upselling" offers at the time of initial signup will slow the order process and make it more potentially difficult for the typical non-techy customer, who just wants basic hosting and a domain, to understand.
There's a reason why you see the largest web hosting providers have a very simple and basic order system. You normally can't add anything except hosting and a domain name. Upselling is something they do later... once the customer has become a customer.
The idea behind this is to completely remove all possible barriers to completing the initial signup process. Giving the new customer too many options and choices makes their signup confusing, and increases the likelihood they will abandon the process. It is better to upsell *after* they have bought something and have already become emotionally and financially committed to your company. Now you can sell them all the other stuff.
So it is MUCH better, in my opinion, to have a system where the initial order is very basic. Then after they order.. wait 24 hours and your system then starts sending them applicable product upselling offers.
So for example, I think the best sort of order and upselling system is like this:
1. Customer uses super simple order system to purchase a domain name (or transfer) and web hosting. (See the other current thread about simplifying the order process to just those basic steps. One single simple order page. Done.)
2. Now customer has paid and is committed to your company financially. They are emotionally invested. So your system can look at what they purchased and send out an email offer with discount codes or whatever to upsell them on other stuff. You can run these "offers" at any time at the push of a button.
I hope that makes sense? I'd rather see Blesta be able to handle step #2 above, which we can then run at any time, then to integrate this into the initial order system, which would likely do nothing but confuse most of our customers (who are non-technical).
So... Step #2 would be settings in Blesta where we can specify things like IF the customer has X product AND NOT Y product, THEN send them a sales email offering Y product with Z discount code. This will be much more effective, and will result in more initial signups *and* more purchases of the upsell item.