In Chapter 1, we are given a long description of Jurgis and Ona's wedding. However, we are not given an exact dollar value as to what their specific wedding cost.
We are told that, at weddings, the guests are expected to contribute money to help pay for the festivities. We are told that the contributions will generally come to somewhere between two hundred and three hundred dollars. As Sinclair tells us, this would be more than a year's income for most of the people who attend the wedding. Later in the chapter, we are given a partial breakdown of what has actually been spent at this wedding but it is very incomplete and does not tell us the full cost of the wedding.
So, we are left to assume that this is a typical wedding that will cost between $200 and $300, but we do not know the exact cost.