Local fish store would be best. Not many online sellers who sell them direct. I think sometimes liveaquaria will have them in their what you see is what you get (WYSIWYG) section
Can I put just one angle in 60l tank? I also have 7 neon tetras, know that a big angel can it them, but heard that if we put a young one and it grows with them it won’t reckon them as food
yeah if your angel is small and grows up with the neons, then it wont eat them. And the the neons also should get bigger. So yes you an put a angel with them