I only have experience of Customs from the UK, I'm afraid. It CAN be ridiculous (I'll give you an example below) however, from my experience, if the seller/overseas retailer puts a $ value of $15 or less, customs won't look at it. Also assuming, as most figures do, it doesn't weigh too much either. Hope that helps!
Meanwhile, a general question to all. Concerning what you would consider "reasonable" charges for shipping. Super7 have recently revealed an initial set of four shot glasses with G1 Artwork...
Now they are priced at $12 each. Which well, is a little high, but bearable. So the whole set will naturally fetch you $48. Still less than an MP figure and a little bit more "adult" as a display piece.
So, the big question. How much do you think they are asking for in shipping? $15? $25? The ballpark average most would think of, yes?
How about $70?!
Nearly twice as expensive as the glasses themselves. $70 (and change) to ship four shot glasses...