That's the most one would pay. I am not going to go through all the rules again, but just note:
1. post offices and clerks differ in their interpretations of the rules.
2. on-line rates are cheaper than using stamps or paying the post office clerk.
3. putting strong, inexpensive chips in letters (no more than 1/4" thick) is the cheapest way. (I wonder if a bubble mailer could be considered a letter.)
4. $1.95 and $2.12 are first class parcel rates, more costly than first class letter rate or first class flat rate.
5. you could argue that first class FLAT rates should apply to the bubble mailer.

Robt.