Lets say one would like to find a type of bisamim that is lechatichila the bracha of minay bisamim, so that its easier to reach 100 brachot each day (4 foods and 4 bisamim- hanoten, atzey, isbay, minay ) but then learned that nothing is good to make a minay bisamim on if one is already doing an atzei bisamim and isbay bisamim. Then they learned in rambam that authentic musk oil is minay lechatchila, and wouldnt be already "covered" with an atzei and isbay. Turns out though thats extremely expensive. So is there anything like musk oil for this situation or is that the only option?

ב"ה Shalom, On a regular weekday one can reach more than 100 Berachot just by Davening Shmoneh Esreh 3 times, and the rest of the Tefila, saying the Brachot before and after eating etc. (See Mishna Brura 46:14 for a full account) . On Shabbat to complete the 100 Berachot, the Mishna Brura mentions different options. However, he does not mention a requirement to make all the Berachot for fragrances, "Atzei", "Isbei", minei". Making a Beracha on Besamin is only mentioned by the Mishna Brura as an option to complete 100 Berachot on Yom Kippur, when we are really in a "Beracha shortage". In addition, the Magen Avraham says that one should be careful NOT to say unnecessary Berachot just to reach 100. Indeed , in regard to musk oil, the Rambam (Hilchot Berachot 9:10 and the Shulchan Aruch (Orach Chaim 216:b) , mention musk as an example of a fragrance which is not from a tree or the like, but from an animal upon which one would make the Bracha "Borei Minei Besamim" to begin with. I personally am not familiar with fragrances which come from animals which are available for people to bless on. However, in a short browse on the internet I found that there are such fragrances which would qualify for saying "Bore Minei Besamim" , however they are very hard to come by. All the best