Originally Posted by
milepig
I think one issue with that approach is that the one-way return fare is unlikely to still be available a the current price when the OP is ready to make a decision.
At a minimum, the OP would want to take a look at that particular market and get an understanding of how far in advance you typically need to buy a one-way ticket to get fares in that range. Nothing's for certain of course, but if you feel comfortable that by January you can lock in your exact date in March (to use a hypothetical), it might still work.