I bought a ticket last year ORD-Jakarta/Bangkok-LAX for $495 (Well to be completely honest I paid for it with 33k UR points). This was on JAL. I also bought a RT to Bangkok last year for $530 on China Eastern (also with UR points). This is an example of where UR points are awesome. A SE Asia ticket costs 80k on United, plus tax, and you receive no miles. I got the ticket, and a few miles (not many because of the really low discount class) back to boot.

So while I think $200 RT sounds like an award ticket with taxes, $400 is probably within the realm of possibility.

I haven't had much trouble lately finding these cheap fares. Typically I search using Momondo and Google Flights. If you don't see the China Eastern flights you aren't looking hard enough. They only fly out of the big cities as well. Other airlines sometimes try their hardest to match the price of China Eastern, so it might be possible to pay a bit extra and not fly China Eastern. This is recommended!

I am guessing you don't care (nor do I!) but China Eastern is not the most pleasant way to fly. Chinese airlines don't allow you to use your cell phone on the flight, so you have to be like the guy who posted that he puts a blanket over his head and uses it under the blanket! They run out of booze seemingly immediately after dinner (3 hours into your 13 hour flight!), but at least its free food and drink I suppose. Transiting in Chinese airports isn't much fun. On the other hand, China Eastern planes I've been on (international long haul only) have been pretty much brand new.

There are two really good sites to keep an eye on cheap fares, and others deals that come along. Be aware when they have a "mistake fare" that airlines pretty much always cancel those flights now.

Secret Flying | Cheap Flight Deals
https://www.theflightdeal.com/

Happy hunting, let us know what you find!