IMHO it would be better for you to take the vehicle to a body shop (different than who did the work) and ask them to check the quality of the job, look for previous repairs/body work, and any old or new rust that needs fixing, then ask them how much it would cost to fix everything.
Copy what I wrote above and print it out, that's at least a start for where to look for rust.
More photos of the vehicle would help ie: front, sides, rear. BTW it appears to be missing a headlamp "eyebrow" piece of chrome in the photo above.