If ye know anyone else who's also going that way on the same day, ye could always see if GroupSave is available for that route. If ye got one other person on and split it between the three of ye, it'd work out to about £48,- each.
By the by: Looking at Avantix shows the cheapest available single fare (Not including advance tickets) to be £80.70 for an Any Permitted route. I take it ye are looking at Advance tickets there?
Addendum: Actually, a quick look at Avantix manages to get that down to
£44.20 each if ye travel via Preston and Burnley - Which'll save ye £55.60 off those pricy East Coast fares ye were looking at! 8)
Here's the list (Priced per person, no railcards):
- £30.40 - CDS: Edinburgh --> Preston. Route: Carlisle. Restrictions: B1.
- £13.80 - SDS: Preston --> Halifax. Route: Burnley. Restrictions: None
- £44.20 - Total fare per passenger. Saving £27.80 per passenger.
Period returns available along same split route, starting at £69.80 per passenger.
There might be a better way of splitting it for cheaper fares, but I'd say this is a good start!
That said, the fares I've given ye might not be valid that early (Though it's worth checking). Also, don't forget that there might be strikes on this weekend, so check before travelling!