Oomis,
Firstly, you’re comments here are always so intelligent, that I’m truly surprised at your advocacy of people abdicating their responsibility to pay for services rendered.
Regarding the “in which which sefer does it say you have to pay $2000”, that is truly a puzzling question. In which sefer does it say how much to pay for the wedding band? For the caterer? For the gown rental? For the invitations? For that matter, in which sefer does it say how much to pay your cleaning help? Your hairdresser? Your electrician? Don’t most people understand that they need to pay for services rendered? Except for the most “Es kumpt mir” type of person, most people know that when they use a services, they pay for it. Even if my neighbor, an accomplished plumber, fixes my bathtub, I will still make sure he accepts a regular fee- I’m not looking to get out of paying just because I have a good relationship with my neighbors. Kal vchomer someone who is not my neighbor, and who I call specifically because he/she is known as a shadchan, with no prior friend/family relationship! (I would still pay my friend/family the appropriate fee, as I do not get any satisfaction out of “getting away with not paying”, and if they refuse, I would send an expensive gift).
As far as the family not having the money for ANY of those things mentioned, that means they are not doing those things. If there is someone who is not having a band or a caterer for their wedding, they might also not be able to use the services of a shadchan. Or, just like their might be a tzedakah organization in town to help with the caterer expenses, the family might need help with the shadchan fees. A nice shadchan who knows that a family will likely be needing tzedaka funds to finance a basic catering package might offer a discount on shadchanus fees, in order to do their end of the tzedaka, but that is what it is, tzedaka. The shadchan is no less an important service vendor than the band.