Virgin is now $140 per extra bag.
You can gamble, but I really mean gamble... by taking a packed smaller bag and seeing if you can take it onboard. I honestly did this - thinking it would be my carry on - but the moment I stepped inside the terminal, they insisted on weighing it (all I was concerned with and read about had been measurements, not weight), and it was too heavy to carry on, so they made me check it.
I was genuinely upset, but played up a bit, and the gentleman checking me in looked at how small a bag it is, plus, the porter was there, who had helped me try to repack things, and we both stated that even if the bag was empty it would be too heavy... and the check-in guy took pity on me and didn't charge me.
But who knows.
Overall, I think it's cheaper to ship.
Also, my friend, LittleNicky on here, is in the process of moving... you might send him a message asking him how he's going about it. I think he found some deal, but it's got restrictions on size. I'm not sure.
And be careful what's shipped by ground; I did that with one box, and it looked like Ace Ventura had been in charge of it... kicked around, other heavy boxes tossed on top of it, etc. I got a couple of cracked tape/ cd cases, etc.