I'm looking for a mid-range CIEM myself and I think it's worth taking a look at some of the less famous brands. Like Rooth, 1964ears etc. In fact there are probably dozens of customs that fit your budget if you're willing to take a little more risk, so perhaps you should try to look for iems that fit your preferred sound. I suppose you could also visit Jaben Thailand if you're in Bangkok.
From reading what other people write, I gather that people who are perfectionist need to read "build quality is good" with a bit of scepticism, since reviewers generally overlook small bubbles and a little cloudiness in the translucent/clear coloured shells. Then there are companies like UM which reviewers typically describe as having "flawless shells".