Potential Sponsors are EVERYWHERE!
The first rule of getting sponsors is "Highlight what is in it for them!!!"
I have found the best place to find sponsors is at trade shows. Talk to the people that are at the booth at a tradeshow where they are pitching or promoting a product that would be of interest to your group. Ask them some pointed questions and develop a conversation about supporting the community. Some opening statements / questions might look like this:
1) Hi, My name is Dan, I was wondering if you guys support the community and if so, whom I might talk to about getting your product messaging in front of my community organization?
2) I am the President of a local user group community called "Fill in the blank (Virtualization Group Boston)". I have about "xxx 500 members". We have regular training sessions to learn about virtualization topics and I was wondering if you guys would have any interest in reaching out to my members?
3) Hi, I am coordinating an event in a couple months called Virtualization Deep Dive Day where I will have about 150 of my members attending. They are there to learn about virtualization topics and I was wondering whom I might reach out to in your organization to see if you guys are interested in participating?
You can use these question techniques in any setting. I strongly recommend you to not embellish on the truth. If you do that, you will ruin any possibility of continued support. More to come later on this topic but bottom line, once you get a sponsor, you want to keep them and have them contribute more over time.
Running a user group is a relationship business. Think in terms of developing relationships as you progress. Even if someone is not interested now, they may be in the future. If you are really uncomfortable with all this stuff, you might want to pick up a book or two on "Basic Sales Techniques". Develop your elevator pitch and build on it as you gain more experience.