Gardyloo is suggesting you look at the LCCs, which will sell you a 1-way for zero-premium. www.whichbudget.com will give you the options. Also try airmalta.com which will do a decent 1-way fare (via malta though).

If you have any orphan miles sometimes miles+cash are decent value as the don't penalise 1way (eg BA would be 15k miles and £40ish+tax, except that they have no availability in August ).