Hey Chip,
Thanks for the link. That looks like a fine Antenna.
Yes you can use a cheap $10 standard antenna, but you may be disappointed, depending on the strength of local FM signal.
What is important about the Antenna in the link is that it is not a 'Ground Plane' antenna.
Have you ever noticed local delivery companies have a whip antenna in the centre of hood of the car.? This is because of the 'Ground Plane' it provides.
Mounting a normal antenna on it's side will greatly reduce it's effectiveness. You will also likely notice reception is better in one direction over another. Having a good antenna on a long trip is a blessing, especially in Canada where you can ride for several hundred miles with no reception.
The Antenna in the link you provided does not require the same ground plane. Interesting spin they have put on it though. ALL signal is with reference to ground. The 95% shield they use is a ground shield.
I'll wait to hear if others have recommendation they like, but I'll think I'll be ordering the T-Antenna for inside the IS fairing.
http://www.antennas.us/store/c/28-ANTENNAS-by-Frequency.html provides some insight into Antennas.
Different applications need different antennas. I for one would like to find a good small CB antenna for the Interstate. Doubling up with the (normal) FM antenna can be done, but it really compromises signal strength for the CB, greatly reducing signal strength and range. I am considering one of these for that job
http://www.cbcity.com/category/Antennas-32All the best.
Glenn