When done right and not abused, sponsorship is a mutually beneficial and fun way to "spread the love" of great kit and top talent. Most companies in the industry try to keep a bit of their advertising budget free for talented modders, and feel it's part of giving back to the consumers who spend so much on their products.
On the other hand, when it's clear that it's all about the free kit, the whole of modding suffers. Companies waste budget on people who never intend to finish a project or do a lousy job, and then don't have anything left for the people who do finish great work. Both sides get bitter and, in the end, it's the art that suffers most.
If you take your time, have patience and accept that sponsorship is a business arrangement and not some magical money tree, you'll find that there's plenty of help around. Who knows, maybe you'll just find a PM in your inbox from me, wondering about featuring your next project.