1. PhD ekak cost eka aduwen krnna puluwn mona wage ratawal walata?
2. Khmda apply krnne?
3. PhD eka krana kaale job krnna puluwnda?
There are two steps
(a) enrolling the university PhD program (in some counties like Canada, you cant directly apply for PhD. You have to have a msc or apply for msc first. You can sometimes transfer from Msc to PhD without completing msc.)
(b) get the financial support
(b) is the most difficult thing, although we can get admission from many universities. In Austraila, Europe, there are limited scholarships but it is very difficult to get them (correct me if I am wrong). In Canada, sometimes professors have funding and they can get students with financial support
So first, go through university websites (and professor's webpages) and see if you are interested in their research areas. There are sri lankan professors as well. Write to them (say that you are interested in that area, your academic qualifications and asked if there is an opportunity for higher studies). Also there can be sri lankan students (you can get info from them as well)
I know this is not straightforward and takes time (sometimes very frustrating) and have to do some research. But keep on trying (don't give up). There are many sri lankan profs in outside sri lanka.
If you go to higher studies in countries like Germany or Japan, you many need to learn the language (for everyday use, although it is in english medium),
Doing a PhD and working as a part time is possible but with limited hours. That can be difficult. Many work as lab assistants. Also you can try industrial funding during the PhD.