Any truck stop has name brand and cut rate antennas. I see Diesel brand antennas has a mag mount for $25.

Word of Wisdom. Only use a mag mount where the coax is laid as smooth as possible. Don't use a mag mount in place of a trunk mount. If you use a mag mount, the coax flops loose and gets pinched and damaged. The trunk lip mount has a frame that keeps the coax stable when opening and closing the trunk and keeps it from getting bent too much causing the SWR to go nutz as well. ebay has trunk lip "new/old" stock hustlers and such for a good price. I paid $35 free shipping for a hustler trunk lip just a month ago. You do have to look at ebay 3 times a day and be ready to jump on it. Things go fast. I lost a couple things I wanted by procrastinating for 30 minutes!