I absolutely understand. I'm not a marketing person either, but I have some experience in usability research, and I think you will get as much value from testing the homepage with a few fresh faces as you would from a marketing project. There is an interesting crossover between usability and product marketing when it comes to homepages and messaging.
If you haven't already, I highly recommend Steve Krug's new book "Rocket surgery made easy", which is focused on guerilla usability testing. Usability testing is classically about identifying problems/improvements to a UI, but you can quite easily use the same techniques to test your homepage and figure out whether people understand the product and whether the homepage encourages them to try it out, etc.
Have fun!