Why use the M4 with its more crowded road and dear 2.80 toll.
From nearby Collinstown I go thru Delvin and Athboy and join the M3 and there's only one toll of 1.40 (Mind you if I joined one exit further north I'd pay another 1.40.)
+ the M50 toll if you are coming from Tallaght......
No toll on M50 coming from Tallaght
No toll on M50 coming from Tallaght