I purchase a lot of items overseas and at first I found it to be a little off putting.
Now, it's easy, I just remember to follow a few little tips:
1) If buying from a country such as the USA, don't be fooled by the dollar amount. For example $9.99US might sound great, but really it's actually around $13.30AUD which may not be such a bargain afterall.
2) Shipping costs: Shipping can be quite expensive, if the seller only provides one flat shipping rate, ask if there is another option available. Surface mail is a lot cheaper than Global Express, but obviously it will take longer (up to 12 weeks insfact). Global Express will provide an online tracking service with insurance but is very expensive. Airmail is another option, it's cheaper than global express, only takes a few more days to be delivered but does not provide insurance or online tracking. If you opt for additional insurance, you may find that it would be cheaper to go for global express. The seller may be able to help, so ask them and find out.
3) Customs tax: Yuck !! I have been hit with it a few times in the past and boy is it expensive !! I have now found that if I spend less than $250US on purchases and shipping, the package will generally slip through customs no worries.