Virtual stacking is a fancy marketing term that does not involve any action from the administrator. It simply means you can edit all switchports from all switches in one dashboard network.
The actual stacking methods are:
Physical stacking (with stacking cables in 0.5m, 1m or 3m variants) which confines your switches to one MS family and physical location in one rack/closet. Exception is that the MS210 and MS225 families can be stacked together.
Flexible stacking: This makes a physical stack between multiple switches that are further apart from each other using normal fiber. This feature is ONLY supported on the MS425 switches and has some resemblance to HP's IRF stack feature since it also supports more than 2 switches. The reason for flexible stacking is that you are more likely to have a distribution block or core switch block that is in a different location to survive physical events in one dataroom.
@Par_23 you would need 10x SFP modules as you need a loop of connections, so each switch needs two. If you speak to a Meraki representative the cost of the DAC cables used to connect the actual stacking ports should be less than the cost of 10x SFP modules and 5x fibre patch cables.