a good way to circument one way fairs is to simply buy a round trip ticket, and "accidentally" miss the return end of the flight. on average round trip tickets are cheaper than one ways.
just a little tip i happen to know
a bit of warning on this, you can be fined / charged for doing that.. also your name gets flagged and it can become difficult to get a ticket out again when you need it. airline companies do NOT like people who do that one bit, because they could have sold that return ticket to someone else for more money.
if you think you might stay for a year but might want to return home, instead talk to a travel agent specializing in discount tickets for the area yo uare going, they are full fare tickets discounted by the airline to the travel agent and therefore have little to no restrictions. this means you can trade your return ticket in for a later date up to 1 year from purchase, usually. make sure you specify you want that as an option when you talk with them.
of course if you are really trying not to come back then it doesn't matter :).