Melissa,
Our school has almost 50% of the student body on free/reduced lunch and therefore the money coming in was quite limited. The primary school of thought for our corporate sponsorship was to encourage businesses in our local area to support the school. Of course, we had to show how this sponsorship would be mutually beneficial so we put together a list of things we could do as a school, to cross promote. Then our sponsorship packages came to life.
One of the bigger sponsorships we have is for our student field trip shirts. This is our second year of securing a specific company to pay for all shirts, allowing us to sell them for $10 each. We have our artwork on the front while the back has the corp. sponsorship logo. Choosing a cool shirt and graphics is key to the sales though - this year we chose a multicolored tie dye and they sold like hotcakes! To get a business on board with this sponsorship, they need to really be advised as to the exposure they can receive - how many students are at the school, how many field trips, etc.
Your PTO/PTA, along with the principal at your school, need to come up with ways you can help promote a sponsors business; logo on a website, decals or stickers on folders, sponsorship wall at the school, flyers to be distributed, etc. The businesses need to be reminded these students are their future employees, or community business owners. Once you establish your program, it will continue to grow each year.
We are now in our 3rd year, just starting our 2nd week of school, and we have already secured 15 sponsors for a total of about $15,000. We have 5 different sponsorship levels this year ranging from $250 - $5,000, appealing to businesses of all sizes. This is extremely important to your small business owners knowing they are able to participate.
Good luck! Please feel free to contact me with any more questions.