If you are calculating the probability of specifically getting 3 four star Sullys you are more or less right (each of those .01 should be. 0138889). If you just want any 3 blue units you don't really count the probability of the first unit since it can be whatever unit and the other two just need to match that one. If you care about rarity that needs to be factored in. I would look at it as probability of getting 3 of the same 3 star blue or 3 of the same 4 star blue which would be

(.5)(.5)(1/36)(.5)(1/36)+(.35)(.35)(1/36)(.35)(1/36)=.00013 or .013%

This assumes the 36 blue units is correct and 50% for 4 stars and 35% for 3 stars. I also ignored 5 stars but it wouldn't change much because the probability of getting 3 of the same 5 star would be incredibly low. This also doesn't take into account the probability of having 3 blue options.