Just about anything is possible if you can imagine it. However, to grab values like that would require a significant amount of code. The variation you're asking for makes it more complicated. If you had 2 textboxes for low to high values it would be easier to loop one by one from low to high. Putting it in one box means having to parse the values. If they're separated by dashes there's a range you'd have to loop through. If separated by commas they're individual values that have to be looped through. I think you'd be better off with a continuous or datasheet subform where the user inputs every value and you loop through the records. Alternatively, same type of form but 2 fields - 1 for the low value 1 for the high. If the high is null, it's a single value in the first field. Still, seems like a code solution, but then I'm somewhat biased in that regard!
Maybe you will get other/better suggestions.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.