Hi,
Seeking for $30~50 range blanc de noirs champagne to stock and enjoy once a 1~2 weeks.
I really fell in love with BdN champagne and been keep enjoying it, but found that it’s really threatening my wallet 
I would appreciate any recommendation.
Thank you.
Marie Courtin!
Depending on which style of BdN you’ve fallen in love with. Most BdN is often more vinous, slightly more oxidative, nutty and perhaps a bit lower in acidity than your typical Champagne, but there are lots of examples that are not that obviously BdN in style. For example I do love Marie Courtin that Curtis here proposed - they certainly are wonderful wines, and definitely worth checking out - but I don’t think they are that typical for BdN, as they are often quite delicate, precise and mineral in style.
For a budget version of classic, rich, vinous end of the BdN spectrum, Fleury’s Fleur de l’Europe and André Clouet Grande Reserve have been reliable choices for everyday purposes. Nothing too thrilling, but won’t break the bank.
Gonet-Medeville
Not sure where Paul Dethune’s BdN is right now pricewise but for me it’s one of the benchmarks.
Not technically a BdN as it has some white grapes, but I’ve always liked Billiot. Even with 25% Chardonnay, I’ve always found it to drink like a BdN, with that vinuous style Otto mentions. I also like the Marie Courtin and Gonet-Medeville previously mentioned, and have not tried the Dethune.