Sometimes you don't really need a macro lens to make such pictures. For all these rose's pictures I used my kit lens
All I had to do is to take it off and turn around.. and Magic! Of course it can't be compared to a real macro lens.. because you have to hold it tight to your camera and you can't use an autofocus all you can do is to move closer or farther to the object and catch a moment and than snap. I also had to put ISO 1600 and after I used Noise Reduction Filter in Photoshop to make it look a bit better.
I found that they also sell reversible rings for the lenses. You can follow the link and check it out
Have a great weekend :)