Shel has bought two new mobile phones on ebay (both from hong kong *gasp*!) and the only problem she had was whe she bought the second phone the seller forgot to put a usb cable in, which was easily sorted out and we got the cable. [We had some problems afterwards with the seller, but there was nothing wrong with the phone]

It's not too risky as long as you know what you want and read the fine print. Some phones on ebay are locked to a particular network, and charge extra to unlock so make sure you read everything and make sure its unlocked. Make sure they offer registered post and postal insurance. Check out the postage costs, because usually thats where they catch you. Make sure it comes with a charger, usb cable, battery, driver disk for the computer. If it is from overseas, make sure they throw in an Australian adaptor, because their phone chargers are often overseas plugs. And make sure the software is in english (i had this problem with an MP3 player i bought from china!), had to pay them extra for english software!

Good luck!