If you don't want to spend the extra for a hitch, or have decreased visibility of a rack that hangs on by straps, then there is always the roof rack option. This can be a cheaper option if your Subaru already has a roof rack installed from the factory.

Roof bike racks do have some issues.
1. Disturbs gas mileage.
2. Can be noisier.
3. Bike bug splats (but you can get a fairing).
4. Can be difficult to lift the bike up to the rack. Fortunately your Subaru isn't as tall as some SUVs and vans.
5. The dreaded "drive it into the garage with the bike on top".