Have either of you done a compression test? That would allow you to trouble check a lot of your assumptions. If you haven't yet done the compression check...why? The testing equipment is cheap, especially in comparison to needlessly buying parts that are perfectly fine. Compression test, compression test, compression test!

On to the motor mounts, you always want to check the motor mounts before buying new ones. $58 might not seem that much, but if you don't need it, don't buy it. All you have to do is raise the car on stands, then raise the engine just so that no weight is being applied to the mounts. Visually check the mounts for cracks (they generally crack in the center) and looseness in their plates by using a large screwdriver to attempt to move the mounts. It could be that the fasteners have come loose.

If you do have to replace the mount(s), always be sure to apply rubber preservative to slow deterioration.

Once again, COMPRESSION TEST.