Take the Thailand (English) edition of Robb Report (pictured) - it is actually printed in Malaysia. Until a few years ago Property Report Asia magazine (also in English) was printed in Singapore (it could still be) - and both will undoubtedly have chosen their printers because of speed and costs.
Even with the associated shipping and import costs, if often works out cheaper to print outside the Kingdom. That said, both magazines to have relatively high cover prices (at 195 baht and 200 baht respectively) compared with the locally-printed titles.
In terms of printing magazines, Thailand is not as cheap as some of its neighbours - and not necessarily the ones you would immediately think of.