Negotiation - an art

I always feel negotiation is an art- which you have got to do - whatever you are or whoever you are. My profession has given me lots of chance to do that and i always feel my performance is below par everytime- but better than the last time. Due to my profesion and job profile- i do negotiate with- scientists, science adminstrators, various indian business luminaries. I cannot tell names and all over here- but here is the sample of one that was a small deal and happened recently [ When i put it on writing- it appears- so silly]

I have already sold the customer- some products and services worth nearly $390 K; but I am trying to sell him an addon service whose proposed value is nearly Rs 5,00,000 ( small change!!!). there is a tax component of 10.8% added to that.
Customer (C)- Sambit, this is unfair, and unrealistic....
Myself-(S)- You are right C, so many things in this weird world are..
C- (laughs....heartily).. comee onnn boy give me a break this component service should come free to me.
s- No C, cannot do that. I need 5 + taxes.
C- no discounts.
s- ummmm... sorry no.... cannot -- you know- it is as bad as loosing my face and job.
C- it is always ur job which is under fire... i need to save mine too.
s- I understand........ sighh... (deep sighhh follows)
C- give some discounts..
s- ok what you want (resigned to fate kind of voice)
c- what is your offer.
s- it is useless to tell you- you tell me what you want
c- I donot know---- can you absorb the taxes..
s- If i say yes- when i can expect this to materialise.
c- by 8 am tommorow.
S- done...but i want it by 8pm tonight. can you do it.
C- done- will do that..

I feel he went home happy... and i am always happy...