Defence Language Institute now has some texts in Turkmen

Check it out, now the DLI's Global Language Online Support System page has a few texts in Turkmen - four in total. I haven't kept an accurate check on exactly which languages are there but I'm fairly sure that Turkmen is the only language that has been added since North Korean (not a different language from South Korean, just Korean with a few differences).

Turkmen resources are still extremely scarce though so for anyone going to Turkmenistan that only has access to online resources I would still recommend sticking with standard Turkish as much as possible, and then only switching over to the limited Turkmen resources out there about two weeks before leaving in order to learn about how they differ. Back in 2008 I wrote a post about how Turkmen and Azeri can become quite legible to a Turkish speaker simply by replacing letters here and there, so going all out on standard Turkish and then following it up by getting yourself used to the different orthography and some other differences is usually the most effective way in a pinch. A quick text replacement turns this:

Garaşsyz we baky Bitarap Türkmenistan döwleti Gundogaryn we Gunbataryn kop yuertlaryna tarao gidyan gadymy “Beýik Ýupek” sowda ýollarynyň çatrygynda, geografik taýdan innan amatly ýerde ýerleşýar. Şona gora-de, Türkmenistanyň territoriýasynyn usti bilen Gadymy we Orta asyr dowurlerinde hem dunya bazarlaryna tarap kerwen yollary, yodalary gecipdir.

into this:

Garaşsız ve bakı Bitarap Türkmenistan dövleti Gundogarın ve Gunbatarın kop ıuertlarına tarao gidıan gadımı “Beyik yupek” sovda yollarının çatrıgında, geografik taydan innan amatlı yerde yerleşyar. Şona gora-de, Türkmenistanın territoriyasının usti bilen Gadımı ve Orta asır dovurlerinde hem dunıa bazarlarına tarap kerven ıolları, ıodaları gecipdir.

which is not perfect (especially yodalary to ıodaları) but overall much easier to read if you know Turkish.