I have the same issue on my 01 i30. Mine is quite bad to the point that I am getting afraid to drive the car for fear of my engine falling out. I just took it in to a local body shop this week and they quoted me $817 to replace it with a factory replacement support beam. The part is only around $220...the rest is labor.
I noticed in the comments of maxhopper's video someone recommended a Safe T Cap from Autorust.com. It's basically a band-aid for this type of situation, but it's only $100. I actually just sent them an e-mail for some pics and labor estimates as neither are listed on their site, and they also just list it under Maxima, with no year specifications. In my situation this could be just the ticket as I am looking to trade-in for a new car later this year. I need to do something to address the issue in the meantime, but really don't want to dump nearly a grand in a car that is hardly worth more than that.
Here is what mine looks like:
