I am always attracted to a potential bargain buy myself. You say the Hawken looks good other than the barrel, so in this case I would say:
1. The barrel may be salvageable to the point that it would shoot well enough for a hunting gun.
2. You might be able to pick up a cheap replacement barrel on ebay or some such place later on.
3. The lock alone if in good condition could be worth $100. The other parts, such as the rest of the furniture, sights, triggers, etc. add to the value.
In short, for around $100 it's hard to see how you could go wrong.