There are two types of ways you can use velocity points.
Either a true ‘award’ seat, which is priced according to the redemption tables, OR use your points as quasi cash.
In the latter, points are worth about .6cents each. Virgin is offering you the chance to buy a regular paid seat using your points, but at the .6c rate.
True reward seats are very limited, maybe only one or two on each flight in premium cabins, and maybe a couple more in economy. They get snapped up fast. True reward seats are seats the airline doesn’t think they’re going to be able to sell, so they make them available as part of their FF program.
The cash fares/rewards are pretty much unlimited, based on the going cash rate at the time. You’re simply using your points to buy a normal airfare.
In your case, if the going cash fare was $2800, at .6 of a cent conversion, it works out to around 466000 points, give or take.
If you had been able to find and book a true award it would have been just 65k points. Plus taxes and carrier fuel surcharges.