www.makemkv.com

Is $190 a reasonable price in June 2026 for a brand new LG BP50NB40 that has been "professionally" flashed to BU40N?

No.

If you plan to use it to rip 4K expect it to be dead in a month or two. You will absolutely end up buying twice purchasing one of those drives. They are bottom of the barrel LG dogsh*t. Someone will inevitably reply claiming they've ripped "hundreds" of discs with no issues using one of these drives but there have been countless posts on the subreddit of people buying WP/BP50 or BP60 drives only to have them die in the first month or two. Just some friendly advice.

I wouldn't sign that flatly. But that is also a bit of a question of faith.

The BU40N (which is installed there) is the best LG drive, also with a view to the longevity,

But $190 is too expensive.

Better to buy a used drive and flash yourself. Great information can be found here in the forum.