I'm US based and traveled a lot pre transplant (40-43 yr old healthy otherwise). Generally I paid about $200-$300 USD for in center HD treatments when traveling abroad (Buenos Aires, Chile, South Africa, Singapore, Portugal, Spain etc...) - except for Canada - Montreal $700-$800, Brussels 500 Euro and Ireland (hard to find spot) 400-500 euro. Those costs do not include IV medicines that are normal in my center, i.e. Epogen and Iron.
I would think that at a lot of these centers you could get a much lower price for longer term care, my treatments were always three sessions or less. I was happy with in Center treatments. Most centers are setup relatively similar to my home center, a few had older machines but they were still clean and the care givers knew their job. I never worried that much with treatment even when there was a significant language barrier.
The key to travel is to be generally healthy and to be experiencing tolerable dialysis treatments - i.e. get to a point where you are generally medically stable.
The site
http://www.globaldialysis.com/ has a center search functions that gives contact information and some centers have reviews. Also the closed Facebook group "Dialysis Traveler" with 519 members (they let new members in, some people don't want the posts public) have a lot of UK folks that go to warm Mediterranean centers in places we don't think about like Larnaca Cyprus, Crete, and Benidorm. For my research I usually used the global dialysis site and each countries local NephroCare (Fresenius) website, i.e.
https://www.nephrocare.pt/ (Portugal) or
https://www.nephrocare.co.za/ (South Africa).
Also make sure you look at our travel forum:
http://ihatedialysis.com/forum/index.php?board=53.0