What to do, what to do... (Thinking of buying a Subaru)

I went and looked at this Subaru RX today. I'm thinking about getting it. I'm sure it can be had for less than $100. The lady that owns it is the original owner, and it has had all the proper service done since it was new. (Checked the records at the dealer where I work.) It recently failed the PA safety inspection because there is excessive rust on the car. (On the underside.) I was thinking about getting it, and using some bondo and undercoat to cover up the rust enough that I could get it to pass. What do you all think?

Here are some pictures.

Mike