I think you should buy one of those expensive vacuum seal units that people use to seal and store food and vacuum seal that sucker.
Seriously, I had one hanging on my garage wall for years, and it didn't rust. The main thing is to keep it in a dry place. So unless it's going to be outside, all you need to do is wipe some oil on the bare metal parts, get a trash bag or two and stick it in that. You don't even need to spend $1.50 on clear wrap or an expensive spray.
If it keeps you up at night, open the bag once in awhile and check on it to make sure the rust didn't eat up the entire manifold, haha.