I picked one up via Amazon ($50-ish) - took about 15 minutes to set up, from the time I opened the box until the time I called. Totally painless.
The box is tiny, like a deck of cards, you could throw in your bag for travel and the charger is a 110-220v universal type.
You plug an analog phone (or hotel phone) into it, it's like a magicjack without the PC need.