Welcome
Personally I use
www.godaddy.com and
www.joker.com - they're something like $10-12 per year and they are all mine, I can move them at will to another registrar, make any changes to the dns, mx, a, etc. records, no questions asked. Service has been excellent. I am sure there is cheaper out there, but I have no need to experiment with my domain names to save $1-2 over the course of a whole year

You'd do well with them with no regrets - I've used them for years.