Kai:

Last summer I bought one of the large size "space bags" to reduce the size of a 2 inch memory foam topper mattress, which is quite bulky. I also use some of the smaller ones to reduce the size of pillows. A vacuum cleaner definitely works better than rolling by hand, but you can get quite a bit of air out of those bags without a vacuum. While there are some 12 volt vacuum cleaners on the market, I don't think they would be powerful enough to really help on the road, and they take up even more space. The problem I had was the bags tend to leak. I purchased a second set with identical problems. My mom claimed she had the same problems with hers too. Seems like within 24 hours or at the most 2 days, air seeps in, which basically defeats the purpose of having them to begin when. Cabela's I think has a heavier duty type bag (at considerably more money). Like a lot of  ideas that start out great, mass production in China kills the quality.  Stay away from the "space bag" brand. My two cents worth.  

Cheers,

Troy