Could I tape a humidifier on the opposite side of the inside of this reed case? Would it work? I wanted to get the Rico storage case with the Rico humidifier, but I already own this case and I wanna save money.

The short answer is yes; however, there are a few factors that may influence your decision. Are you located in an area that has very low humidity (i.e., Arizona or some other very arid environment) or are your reeds stored in and remain in an environment that is air conditioned (which mimics the arid climate by dehumidifying the air) 24/7/365?If so, then a humidifier is probably a thing to do to maintain a constant moisture level in the reeds. If not, then the average humidity in the case is probably around 50% and most humidifiers try to maintain either 58%...not a great difference from the ambient 50%...or 72% which is very moist and, in my experience threaten to encourage mold in your case.As you can probably tell, I'm not a great fan of the humidifiers. I use Protec cases for my oboe reeds (my principal instrument), my Bb and Eb clarinet reeds, soprano, alto, tenor, and bari saxes...for a total of 8 Protec cases and one Rico humidifier case. The Rico was purchased to hold 8 bari sax reeds (at about $3.50 per reed). I was not a happy camper when, in the temperate climate of Toledo, Ohio the almost thirty bucks worth of reeds molded over one weekend.Again, the short answer is that it is possible.

best reeds for beingers for B Flat clarinets

I didn't care for this case but if you are talking about reeds, a beginner should maybe start with a 1 1/2 and then work up as it gets easier to play your instrument.

Does it fit baritone sax reeds

I have the Protec Clarinet and Saxophone Reed Cases. The Clarinet case is definitely too small for Bari reeds. The Saxophone case is probably too small, although I don't know for sure, my Tenor reeds fit pretty snugly.