I have had 2 bikes posted back from the USA for me, and neither were held for import duty or any such stuff.
Both of them were mine and I had ridden them whilst over there, but I didnt fly back with them. Technically I wasnt doing anything illegal, however customs didnt know that. If you could get the seller to put your name as the 'sender' and 'receiver' then it may look more credible, but only if you're sure the seller is a genuine person who isnt going to rip you off.
as for price, factor in about $130 for shipping a bike over here, and thats without insurance (if anyone knows of any cheaper shipping deals then please let me know!). regarding frame/fork combos; a friend got charged the 14% import on a frame/fork set, but successfully argued his case and got it taken down to 4.7%, again arguing will be easier to do if you're not doing anything underhand in the first place!