I have to agree, that antenna isn't worth the effort unless you are very desperate. But, since you have it, there may be a solution for that weak magnet, it won't be very inexpensive though. One solution would be to find a larger, 'flat', magnet and sit that mag-mount on top of the large one, then the large one on the vehicle. That's not a good solution, but it would make the thing 'work', sort of. You can count on having to re-tune that antenna, and that may not be easy at all.
sometimes, those good deals are all that good. Wish I hadn't found that out the hard way...