Hold the phone
Most ARFs are built better than your average kit built by a novice to intermediate builder. I, for one, am completely amazed at the quality of workmanship that is available for under $200. For example, I bought a GP Venus 40 ARF. The 7 color monokote job was beautiful. The trim was applied accurately and with skill. The airframe was light and strong.
Now, that doesn't mean that I don't thoroughly check every ARF and reinforce key areas like the firewall, gear/wing blocks etc., but at the end of the day I am constantly amazed about how intricate and inexpensive ARFs are.
On the used plane front, I have bought and flown many. Our club has a large auction twice a year and well over 100 planes are sold at each one. I've bought everything from older-than-dirt, crashed-and-rebuilt Astro Hogs to mint condition quarter scale planes.
When I buy used planes I ALWAYS bring a fish scale, incidence meter and little dentist mirror / flashlight. With a good inspection you can tell if it's strong and straight. On the rare occassion I buy sight-unseen, I stick to ARFs. Kits are too risky unless you know the builder does quality work.
Jason