Tokyorich: The Bhat Run of a few years ago consisted of folks taking multiple flights on Thai between Chiang Mai and both Mae Hong Son and Chiang Rai.
I myself took a few of those flights during several trips to Thailand.

At that time, the Chiang Mai to Mae Hong Son roundtrip fare was $18, thus the assumption that 1K could be "attained for less than $1000." But what about the cost to fly to Thailand, and then up to Chiang Mai? Today this same rountrip fare is twice that, or $36 (per the Thai website and the current exchange rate of 42.3 bhat to the dollar).

The currrent Chiang Mai to Chiang Rai fare is also shown on the Thai website as $36, although Thai apparently no longer flies non-stop between those cities, and you must now connect in Bangkok. However, if correct, this would be great, as you would accrue four Thai flights for $36. Hopefully someone who has flown this route recently can confirm the true facts.