Bushings usually don't go bad from just sitting, but rubber does dry rot, so its possible.
I would think shocks would be more likely to go bad from just sitting, the strut rod corrodes and then when you finally do use it, the rusted, flaking and pitted rod moving in and out of the shock cuts up the seals and the shocks are shot.
Unless you've decided to just rebuild the entire suspension, I think it would be smarter to inspect and test the parts and find what is really wrong and needs to be fixed. Feeling unstable is not really a good diagnosis technique to figure out if the bushings are bad. It could be shocks, swaybars bushings/endlinks, wheel bearings, ball joints, tie-rods, maybe one bushing is really bad and all the rest are good, it could even be the tires that have been sitting stationary for 2 years.
I'd first put the car up on jack stands and inspect/test/check everything on the suspension, and make your shopping list up from what parts look the worse first. It should be much cheaper and a more likely to solve the problem quicker.