ANOVOS used to make pretty high quality repros but they were expensive and apparently they went out of business, they've been replaced with a new company but no word on whether or not they retain the Star Trek license. I doubt it though, judging what CBS did to Axanar.
You can buy uniforms for about sixty bucks off an official website but they're out of stock now, no telling when they come back in stock or how quality they are.
A quick amazon search only brings up this listing, no telling how good it is but based on the picture, not very.
I got this gold TNG shirt on sale for $10.82 a couple years back. Not sure it's quite worth $30, but with black slacks and dress shoes I looked pretty good.