There are MANY universal windshields that work just fine on the 500. I'm running a National Cycle Street Shield, and it works very well. You may, however, decide after a little time that you actually prefer riding without one. Lots of options either way. There are even a couple of factory Kawasaki shields available, as I understand it.

 

DeniseG,
welcome to the forum.
As Fastpakr said, there are plenty of universal windshields for the 500/500 LTD (what model year did you get? New/used?) The issue is more a limitation to the mounting brackets used to set the windshield to the bike. You're more limited if you buy a quick release type mount, however.
That being said, I got my 2009 500 LTD from the dealer with a Memphis Fats (17" and wide) windshield as I intended to do lots of highway riding and understood the wind at that speed (60 - 70 mph) created the rider "bobble head" effect that also makes long distance riding tiring. I recently took off the windshield because I was doing mostly city and thruway travel. Hitting speeds of 40 - 55 mph I really don't notice much of a difference without the windshield, other than a change in the whistle within my full face helmet. So it may really be a matter of rider preference.

 

Update on the "Riding without a windshield" comment.
I did a round trip between NYC and Boston over the weekend without my windshield and didn't notice that much of a difference with the wind resistance. I also didn't notice much of a "bobble head" affect. No more so than when I had the windshield on and hit bumps and sudden depressions in the road way.
What I _did_ notice, as I rode in 75 - 80F degree late afternoon and 80 - 70 F degree evening interstate traffic was that I had a lot more insect splatter on my helmet and the front edges of my bike than in the past.
Now, of course, it's possible that it's just a fact of warmer, late spring weather as opposed to cold, early spring weather that has brought out the bugs in larger numbers.
But one thing's for sure, I hate wiping insect splatter off of my face shield every 100 miles so I can see at night.

 

windshield

I have a 2009 Vulcan 500 as well. I purchased a Slipstreamer Falcon windshield SS-32 which works great. It covers the wind from your hands as well, which is great for cooler or cold weather.

 

I've tried a few windshields, I have a big one that covers everything, including the hands, and you can't see over it. I use it when the weather is chilly in autumn and early spring. during the summer I have a Windvest that is smaller, more wind in your face but I decided I like that feeling.

One way I kept the wind from blowing me around on my last motorcycle was a set of lowers which I used Harley lowers for, but I am not running with them now maybe because they are harder to fit on this bike.

 

Well, I'm convinced, altho I don't have a windshield. I've run with a toolbag on the bars almost since I got the bike. Recently took it off and it hasn't made it back on. I definately feel more body wind resistance, and I'm more tired at the end of the ride.