Based on the current exchange rate it certainly doesn't look like a good idea to buy in Italy. Hong Kong v US works out about the same (excluding US sales tax). So it depends where you will be in the US.

Also, depending on your employer, it's worth asking in the store in the US whether you have any employee discount programme with them. I assume this is largely for US based companies, but the book they have with all the discount codes in it certainly looks quite large!

For comparison, I bought an 8GB iPod Touch in Dallas about 3 weeks ago. I did get some discount on this, so with the tax it only worked out around 2.5% above the list price. This came out at £149 on my credit card, against a UK list price of £189 (and I think about £169 in Dixons Tax Free when I looked on the way out).

Have you looked at the official Apple resellers in HK? I've used the DG 'Lifestyle' store in Times Square a couple of times in the past and they didn't seem to be forcing bundles on people (I've not been back for a couple of years though).

From a warranty point of view I've never had any issues. I guess it might get complicated if you buy from someone like Best Buy, but I've always stuck to Apple stores or official resellers (HK and US) and I've never had problems. In fact, the iPod Classic I bought in HK 3 years ago was dead when I opened it up back home, and the Regent St Apple Store swapped it out with no problems.