Yeah, Baxter is pretty strict with their camping policy, but that's because it's technically not a state park and gets no money from the state government if I recall correctly. It's all usage fees and a trust fund created by Gov Baxter when the park was created. The camping fees do make life very difficult for solo backpackers, although I think the fee is per site, so if you go with buddies you can split the cost down to a reasonable amount.
Greg, where are you coming from and what's the journey? There are a few other places nearby that make for great backpacking trips without needing to worry about dodging rangers and fees. The Grafton Loop Trail, the 100 Mile Wilderness, and the Bigelow Preserve are all spectacular, and with the exception of one campsite and parking area on the GLT there are no fees.