Yes, I had seen that, this is why I suggested another solution.
With The Prime Host, I would recommend to try first their EcoLevel Reseller Plan at $7.50 per month, allowing a customer to have 25 domains (I have already more than 20 myself).
Then it is always possible to upgrade, but I think the price is very competitive when I consider their quality of service and reliability. It is a small company, but already in existence for 7 years: I have often made better experiences with such small companies (provided they are stable, of course!).
There are several hosting companies offering reliable services for multidomain hosting. I have used several of them, choosing only those which allow to create several individual websites (not subdomains disguising as separate websites!). On which I can recommend, at a very reasonable price (especially since they have frequent "specials" allowing you to have more domains than announced on the regular plan), and which I use currently for hosting more than 20 domains at a very competitive price, is: ThePrimeHost
They are in Texas, and they have a good support, especially considering their very reasonable prices. Also a good forum for finding help if one has a problem. So it would be an option I could recommend from my own experience.
I could also recommend other ones, but they would be more expensive.
[This post has been edited by j_m_fribourg_ch on Nov 5, 2008 9:59am.]