It should be possible to restrict access to any given gallery by using a combination of Framework Builder and Security Assist functionality.
We just finished an additional round of gallery related fixes and tweaks. I'll be posting GMC 2 for testing here in a minute. Release is slated for within the next week if all goes well. As far as pricing goes, I'm not sure what the initial price or the upgrade pricing will be. I'll get a hold of Sales and follow-up when I have some numbers.