Are expensive vitamins worth it?

My hair grows at a somewhat fast rate actually & since I've been taking extremely good care of it for over a year and I haven't dyed it since about Dec 2010, it's very healthy. Straightened, my hair is past my boobs & past my back bra strap(the band).

While I take a One a Day for women multivitamin, ground flax seed & 1000 mcg biotin pill 1-3x a day, I've been contemplating whether or not to buy Viviscal, Phytophanere or Hairfinity to speed growth up a little. I'll post links in an update.

Is it worth it?

I mean, my growth is pretty good & I make sure to incorporate omega 3 fatty acids into my diet on a daily basis, from plant and animal sources.

Yay or nay?
Updates
+1 y
examples:

link

link

link

link
Are expensive vitamins worth it?
Post Opinion