to be honest, it's not going to save you a huge amount of money buying lenses in the US due to the dollar rate. I purchased a Canon 100-400mm f/4.5-5.6 L IS USM lens from Colonial Photo & Hobby when the rate was $2.03 to the £.
If I was buying a lens at the moment I would buy from One Stop Digital (sent from Hong Kong and the guarantee that they refund VAT). I purchased my 24-105mm f/4 L IS USM from them.
If you still want to buy the lens over in Orlando, be careful with the shops on I-Drive - a lot of them seem to be a bit disreputable. I'd recommend colonial, but check their prices before you go !