Not selling. Women can donate eggs but don't sell them. In the usa (not in canada, parts of europe) egg donors are often compensated for their time, discomfort, travel, taking shots etc. But we aren't paying them for their eggs, any more than a kidney should be sold. Compensation may help with college costs, won't pay their way. No money involved for known donors. All are giving a gift: a chance to be a parent.
There are many. While it is a wonderful gift and in the usa one can get paid, there are a number of issues to consider 1. The medical and surgical risks 2. Comfort level with injectable medications 3. Emotional issues and releasing all rights to one's eggs, recognizing that many times eggs can go to non-traditinal family units including single men, workmen, same sex couples, advanced reproductive age.