I have a Renzetti Traveler vise. Bought it used, so I can't speak for its price, but its a quality vise. Wish it was a little higher, but that may have been changed with the newer models.
The nice thing about the Renzetti traveler is that its small and breaks down easy. I would recommend a clap and extention pole. This way you can attach the vise on a picnic table or bench.