While there is merit in your suggestion, I personally feel the Air Corps should only go for new equipment. Or at least equipment made in the last 5 years.
Yes its much more costly, but buying secondhand your merely getting a second rate aircraft that will serve half the time. It would be a stopgap. Paying 3 million for a stop gap doesnt make sense to me.
If the Air Corps have a future in which they support the defence forces abroad, then they need the best, most modern equipment.