Allow to complete xAxis Labels values across the axis for one data point
In a case of one datapoint, a single axis label is presented, and it is quite ugly.
Please supply an indicator to complete at least two 'bogus' labels with automatic relative values (in the stated example - 750 and 2250).
It can be achieved by setting the yAxis.minRange option.
Or consider using minRange, like this: http://jsfiddle.net/p3jrs9g7/1/
You an add an axis min and max if you can check your data values first: http://jsfiddle.net/highcharts/p3jrs9g7/
Another option is to use a tickPositioner callback.
In order to implement a solution like you indicate, we would need to add a setting so that you can decide the magnitude of the additional ticks. For example, if the single value is 1500, we need to know whether to put the extra ticks on 0 and 3000, on 1499 and 1501, or something else (0 and 1500?)