Standard day return fare is £29.60 so yes the day ranger is the cheaper option!
You can get railcard discounts and a family day ranger is the price of two adults (£51.20) for a maximum of 2 adults and 4 children.
Be warned though, its quite a trek from the train station to the football ground.....I did it last season!! Nearly 2 and a half miles each way and takes a good 45 minutes, Nice scenery though!!
No need for the trek...buses run from just up the steps from the Three Fishes pub in the town centre. Takes no more than 10 minutes, even with traffic. Last season, got it around 2.15pm...at the Greenhous for before 2.30pm! Bus stop round corner from ground after into town no bother!
Do be warned about taxis though...call for one around 1pm and you'll get 4pm at the earliest from any taxi company. Bizarre!