likely not worth much, unless they are super rare...autographed Tim Couch stuff goes for $2-$5 USD...I don't think Martin or Davis have much autographed stuff out there, so if those are autos I would guess $10-$50 (depending on rarity) USD, and James autos go $5-$100 USD depending on what it is...
if they aren't autographed or serial numbered, likely they aren't worth the cost of shipping it to the states...
I miss Australia, I was there with the Navy several times, we hit Darwin, Townsville, Sydney, and that lovely whaling community of Albany...I will say, the most attractive woman ive ever seen was in Albany...