There are quite a lot of sellers of simulation-based products, but they need money, and usually a lot. For example, http://www.solver.com/exceluse.htm as one of many) is one of the excel-based ones, but they also provide SDKs.
When I looked at - COIN - OR - COmputational INfrastructure for Operations Research, there was no dedicated event modeling system for their projects. This site is a site for operational research in which they participate, and since the simulation falls under the OR, I looked there.
I think I had a review of Simulation packages somewhere in print, but they were all paid for products, so in your case this may not be an option.