Waterville have an EU membership. Last year it was 30 000 euro to join and 872 annual dues. They must be doing well as they take 6 weeks to reply to emails!
You can apply to Join one of the North Berwick clubs. Not sure of international rate but it will be no more than £300 pa and a similar joining fee. Waiting time 3-5years.
I would also check Portrush. When I enquired about a decade ago, I could join as an overseas member, pay two years at country member rate (£600 from memory) and thereafter the overseas rate, which the Secretary agreed was less than the published weekend summer visitor rate for one round on the Dunluce course! For two courses! If I only had a bit more time!
If you plan to return annually you will make friends and get more from the experience. However I would also want to be near a reasonable size town with a few eating and other choices, you'll be spending more time off the course than on it.