Does “hook it up” mean “give a good deal”?

Hook it up means to attach the cables to something so it works. Hook you up is to get you a good deal or tell you where to get an item.

Metaphorically to hook someone up is to assist them to obtain something. It's implied that you hooking them up allows them to get something they couldn't otherwise get, or at least that you make it easier or cheaper than it would be without your help.

If a friend hooks it up it means he put together an evening of fun that could include seats at a sporting event or concert, got to the front of a line at a popular club, or got the bartender to give a round of drinks for free. it started as a boring night out, and your friend made it a night to remember. If you go fishing and hook up a big fish, you hooked it up. Now he's making sure everybody ahs a good time.