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:
Active Directory management tools for medium sized forest (less than 1000 users)
Are there any tools to do change management with Active Directory / Group Policy?
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?
Edit: Even if this is a pipe dream for us, is there anyone out there offering this type of solution at all?
Short answer is that I think you'll spend more time, effort and money on chasing this than you ever would save by implementing it. There are few products that can unify management of a disparate collection of technologies, and of the few that exist I can't think of any that are inexpensive or straightforwards to implement. They're typically the kinds of products that starry-eyed execs at large companies roll out under the assumption that it'll magically make IT simpler and allow them to lay off some techs.
Given the constraints/circumstances you listed, IMO your best approach would be to focus on reducing/unifying your systems to cut down on variety. Some examples:
These are all examples which will cost some money and effort to implement, but the cost is recouped after the changes because your environment becomes much more straightforwards to manage. Not having to dedicate as much headspace to the exceptions and gotchas of running lots of disparate kit is really good for your stress levels, too.