You can spent between 1 and 8 hundred for one, depending on your ability to pay. The lower priced vises may not be as nearly 'perfect' as the higher priced ones, but they will hold the work.
I only have a PM25, almost a toy, using a $78 4 inch vice. it has the "pull down" component that the $800 vices have, but it's not as accurately machined as they are.