The Just Treats offer is a discount of up to 34% off two green fees - which would leave you paying €59 for a two-ball. Not bad at all when you consider the quality of the golf course - currently being 'tweaked' by Paul McGinley.
Other courses in the area:
Rosapenna (Sandy Hills and Old Tom Morris courses)
North West (links)
FYI - on the Portsalon website they're promoting the following:
Three Day Pass to Rosapenna, Letterkenny & Portsalon only €90.