Giant is a Taiwan brand:
https://en.wikipedia.org/wiki/Giant_Bicycles
But I agree that it is known to be a good brand.
That bike posted is probably really old. I would guess its at least from the 90s and the seller does say its vintage (not like some other sellers that ask for a crazy amount of money for their 20 year old bike).
Up to you if you want to spend the money on it. It would probably suit your purposes if you're just doing easy riding around town. But I don't think it's an incredible deal.
Also how tall are you? I'm not sure about that style of bike but for more recent mountain bikes with 26" wheels, I would guess that a 19" frame bike would fit someone from 5'10 to 6'1.
Here are two more links that might help you research prices on bikes:
http://www.bikepedia.com/ - this to try to determine the year and model of bike
http://www.bicyclebluebook.com/ - to try to get a general price range of the bike
Although when we were shopping for used bikes several years ago, most of the asking prices were way higher than the second link above. Which to be fair they don't provide pricing by area.
Good luck in the search! They say this is around the time of year to start shopping for bikes with the end of season coming.
If you don't find something by then you might be able to check out the bike swap:
http://www.stopswapandsave.com/
Also I would avoid the Black Friday bike deals. We started off looking for those types of deals but as we looked it into it more decided to spend a little bit more.
The more you look into it, the easier it is to keep upping your budget. So watch out for that. And the real good deals on Craigslist goes by fast.
Also here's one link that you can check out for used bikes but they may be higher end up bikes:
http://www.pinkbike.com/buysell/
One more link. If you're okay with a no name bike, people have mentioned this site to be decent:
http://bikesdirect.com/
You'd have to assemble the bike yourself and I may consider getting a bike from there in the future.