Shotgun mic vs lavalier for documentary

@AudioPostExpert: thanks for the clarification on prices, second link redirects to countrymen b6 though not cos-11.

@harmonica: Yes one person per time, just audio, then it will be added on the video in post-production. This documentary is going to be involving indoors interviews only, but if it works the next one might include outdoor ones as well.

As you said I need to choose the best investment for me, i might end up using a lav this time and buying a shotgun mic next (since hopefully i will have a higher budget).

Very interesting video on shotgun mic vs hypercardio:

(the guy mentions that many argue that shotgun mics are not good for indoors because of echoes)

I really like the sound of your video,well done! What mic did you use??