If you're traveling and space is an issue you can look at Tyler Hass' freestyle trainer:
I've come to really prefer rings over straight handles like these though. If you're in the same boat, I like the new straps of Tyler's EXF here: http://ringtraining.com/shop/exf-rings.html
Otherwise Gymnastics bodies has good rings here:http://www.gymnasticbodies.com/store/equipment.html
The prices are all in the ballpark of each other whichever you choose. Some people don't like the three grips of the EXF but really like the strap design. I've yet to see my "dream rings", so I basically get over it and use whatever I've got. For fitness, they are all "about the same", and "about the same price", and certainly do the same thing.
Best of luck.