I had applied for this price through my boss.
still , I think it is better that you give us more information about this question.(as if I used 'for ' instead of 'through', the ststement will be a totally different meaning, agreed?)
I have been applying for the price (required) from our boss (for you).
I have applied for this price with my boss
I have applied for the price to my boss.
I have applied this price from my boss.