For example, a single from Carlisle to Edinburgh leaving at a respectable 9.51am on 23rd December can be had for as little as £8. A return on the 30th December is also going for £8 leaving Carlisle at 9.36am.
Going further South? Travelling between Manchester and Edinburgh is £15.50 leaving Edinburgh on 23 December at 9.51am. It's the same price when returning from Manchester to Edinburgh on the 10.16am train on 30th December.
How about London to Edinburgh, where return train tickets are often into three figures? Well, the 5.48am train to London on 23rd December is £28.50. That same train was going for £18.55 yesterday, which goes to show how prices can change quickly.
Coming from London on 30th December, the cheapest option is the overnight train on the 29th December for £14.50. It's a long trip though: it departs 11.30pm and arrives in Edinburgh at 9.24am. If that sounds like too much of an ordeal, there's a shorter train journey - 4 hours 25 minutes, to be precise - from London King's Cross at 7am which is currently £36.50.
More on Edinburgh trains.