As someone who actually offers OpenACS hosting (www.zill.net),
I am finding that the best way to do it is to have slightly lower end
systems, but dedicate one system to one customer.
No security issues with different users on one box (just the
people from one organization, plus the root user). This has the
added benefit of making it trivial for the customer to do load
testing - since the only site affected is the customer's.
They can set up custom libraries, add whatever other software
they want, etc. It works quite well.
Downside is that it is more expensive (my prices start at $150
per month).
There is a way to offer multiple accounts on one machine. We
have been considering offering it, for about $75 per month.
It is a little difficult to determine exactly what you need for say 10
users - basically you end up being paranoid and adding a little
extra RAM and CPU to compensate for busy periods of the day.
Figure 50MB RAM and 50Mhz to 75Mhz of CPU for each user
(though of course you want a minimum CPU speed regardless).
Could I drop it to $30 per month? Yes - if the demand was truly
there that I could make it up on volume.
So far, I haven't seen that level of casual interest, in terms of
"let's pay $30 a month and play with it".
