Here's a solution that should satisfy everyone,
Allow for a construction time period (yes, just like in the RTS) with a marginal 10%-20% price increase for every vehicle. (Server side setting, obviously, another function being 'Off' unless it's undoable for dev-reasons)
This from the beginning of the game leaves players, at minimum, 15 seconds to wait for their vehicle, meaning more players would go infantry-first at the beginning whilst another team groups up with vehicles.
On some levels where the harvester takes too damn long to move its ass this would give it a 15 second head-start.
Airstrikes become more deadly depending on map.
If you have gone through every vehicle 10 times in one map only then will they be a reflection of 100% price increase as well as how badly one person could be in a vehicle to lose 70-110 vehicles in one game? Hah.
I see more good than bad stemming here, always bear in mind that there is a way to effectively punish the players without dissatisfying people too much, giving them that gamer attitude we all adrenaline rush into at times. If you think the punishment should be more then a mutator is the way to go, but if you punish the player too much the general enjoyment is at a much higher risk of tipping.
[i----Edited : Note -----[/i
Side-note: 1K Infantry could have a waiting time, which could give us all an easier time of balancing mid-tier infantry properly?