I do not believe this is a scam. Many people in Ireland rent out their foreign holiday homes through the internet, newspapers etc. [50% of all holidays booked in the UK are done this way, but in Ireland we tend to need the safety net of a Travel Agent who will usually charge more].
August is only 5 weeks away and even if you book through a Travel Agent they would want all the money upfront at this stage.
If you are in doubt, contact the owner directly and inform him/her of your fears which are legitimate. It would also be a reason to find out more about the resort, apartment, entertainment etc.
I have booked several holidays over the years like this and each has had a happy ending. I will also say that unless I receive a holiday from a travel agent at a knock down price, I will always book with the apartment owner directly.
Best of Luck