"We will choose the best cat, because it is free."
Translation:Roghnóimid an cat is fearr, mar tá sé saor.
There was another real world example of saor meaning "cheap" in a Letter to the Editor of the Irish Times today.
The letter is a followup to a piece on the old narrow-gauge railways in Donegal, and mentions their use to transport people to special events, including one particular excursion on July 22nd, July 1923:
The latter excursion was notable for its advance publicity on separate large posters in both the English and Irish languages. The punchy slogans used at the foot of these posters read: “Quick Service– Cheap Fares” and Seirbhís Gasta–Ticéidí Saora.
For a variety of reasons (one being an awareness that the name Saoirse means "Freedom", and that Saorstát Éireann was known as the Irish Free State in English) I know that I, along with many learners in ireland, assumed that saor means "no charge" when applied to the price of an item or service. But saor really does man "cheap" when you're talking about the price of something - the in aisce isn't really optional if you want to indicate that something is available at no charge (free as in beer, rather than free as in speech).
Note that the it's actually the in aisce in the FGB entry that carries the "gratis" meaning - one example from the FGB is
seachadadh in aisce - "free delivery".
(There's also an interesting example in the EID - "buckshee", a word you don't see much these days!)