Why did they not say how much money they wanted?
Malbim: We do not demand payment for shame and blemish for the past, for Shechem did not know that we object to Orlah. For the future, we cannot give our sister to an Arel for all treasures of in the world.
Why did they say, "Ish Asher Lo Orlah," and not 'l'Arel'?
Ohr ha'Chayim: This teaches that they cannot give to a man who is permitted an Orlah. Therefore, it is not enough for Shechem to circumcise (rather, the entire city must accept to do so).
Ha'amek Davar (to 34:14,17): If the man himself is circumcised, it is no shame to us that he marry our daughter - however, to be Am Echad, everyone must circumcise. They did not say 'l'Am Arel' lest the entire city fight with them. They wanted that at least Shechem circumcise, so it will not be hard to take Dinah. The entire city would not be Moser Nefesh (to stop Bnei Yisrael Yaakov from taking her) like Shechem would.
