I have been having trouble finding Event Reistration solutions that can be hosted in house. I am not overly impressed with services that charge $3-$6 per reistrant when my clients are registering thousands of participants every year. To be paying these kinds of fees rather than using an in house hosted solution with a far lower cost seems much more rational. Most of my clients are already involved in some form of credit card processing.
After a lot of research I was able to find oSComres (http://www.oscommres.com) as an open source solution. The software however is very complex for a client who only needs event registration with simple credit card processing.
Does anyone else have a tool for event registration that is PHP or ASP based?
Thank you in advance for your help and experience.
Aaron M

Have you tried CiviCRM? It
Have you tried CiviCRM? It has a module called CiviEvent that might do what you're looking for:
http://civicrm.org/civievent