There might be. Anytime you buy anything at all from a foreign country, in theory you're always supposed to pay taxes and duty (the rate of duty will vary depending on where the item was made and things like that) on any package valued over $20 (or $60 if it's labelled as a 'gift'). I say in theory because it does happen that packages don't get 'nabbed' by the customs agent and you don't pay anything at all. There doesn't seem to be any rhyme or reason to it, I think it's just because they don't have enough staff to get every single package so it's somewhat random. If you do get nabbed you have to go in person to a postal outlet or office to pick up your package and pay the fees.
Having the person shipping mark the package as a gift is very helpful but companies won't do it and many individuals won't either (it's technically fraud after all) but doesn't hurt to ask. Oh, another tip too, make sure the person marks the value as what you actually paid, not the original retail value, replacement value or price including shipping!!
There's also the possibility of brokerage charges if the package is shipped via courriers like UPS or Purolator. What these companies do is pay the duty and taxes for you and then charge you for the service (usually to the tune of $20-$30 *plus* duty & taxes!). HUGE RIPOFF!!! Not only do you pay that nasty brokerage fee, but you also elliminate any possibility of not paying the taxes/duty. So if you do buy stuff from the US (or anywhere else) make absolutly sure that it's being shipped by the regular post office. If it's a heavy package you might actually pay more to ship via the post office (it's rare but it does happen with larger/heavier packages) and you'll usually have to wait longer for it to arrive, but it's worth it in my opinion, you'll save big bucks!