Thanks for the recommendations and info.
I checked the automated fare calculator that was linked, it seems that the regular fare is 38.70 each way (77.40 total).
However, if I buy online, for two tickets to get to Westport (Dublin-Castlebar and Castlebar-Westport), even with the surcharges for online and credit card, it still only comes out to 9.99 each way plus an extra 7.70 for Castlebar to Westport, or, around 30.00 total. That seems like a big discrepancy compared to the rate in the automated fare calculator, am I missing something?
My planned travel dates are Jan 29 (to Westport) and Jan 30 (returning).