I'm looking for a solution that incorporates most or all of the following:

Patch Management, Server event viewing/tracking, AD change management, ticketing and internal/external kb, remote access - ability to shadow user sessions or create new ones, imaging, and inventory.

Our environments contains Windows Servers and ESXi Hosts (We're not completely virtual, but we're moving that direction). Various Cisco and Linksys switches and firewalls.

This is a tall order, and I don't know if it can be done on a reasonable budget.

I've looked and found some questions on SF that deal with some of this:

http://serverfault.com/questions/72015/active-directory-management-tools-for-medium-sized-forest-less-than-1000-users

http://serverfault.com/questions/4021/are-there-any-tools-to-do-change-management-with-active-directory-group-policy

http://serverfault.com/questions/21752/what-is-a-good-patch-update-management-server

What I'm ideally looking for is a reasonably cheap solution that integrates the features into a central interface. We're a non-profit, so money is a limiting factor (the cheaper, the better; but we have a max of $15k). What we are trying to avoid is having to deal with multiple vendors, while maintaining scalability (we're creating more sites that we'll have to manage).

Is this possible, or will we have to cobble together something to make it work for us?