I ship ramps to Australia regularly and never had any problems. USPS is the best and cheapest way to go. Expect you could ship it easily for $25 or less.....just regular first class mail. You will have to fill out a customs document at the Post Office, but that is easy. Just show it as Pinball Machine Parts. Feel free to put the correct value on it (a lot of folks in other countries ask for this to be reduced to lessen the "duty" they will have to pay). Duty does not apply in Australia until the value exceeds $1,000.00. I ship only regular mail to keep the cost down and transit time has been 6-14 days. It can actually be tracked in the USPS Postal system by the US Customs number assigned.
I don't think you have anything to worry about.