Well is she a US Citizen? The green card application fees are $1490. BUT, you cannot just apply even though assuming she is a US citizen your soon to be spouse. There are other steps you would need to take, to be eligible to file here in the US and adjust your status. Its complicated but it can be done with some smart lawyering and utilizing legal available loop holes. I assume you entered the US illegally many years ago? I strongly suggest you hire competent immigration counsel to assist you with your case. We can help and so can other competent colleagues on this site. Let me know if you need assistance. regards.
You need to consult with an immigration lawyer in the privacy of his/her office. The difference could be being able to apply for your green card here or having to leave the country and apply for consular processing in Ciudad Juarez after the approval of an "extreme hardship" waiver of your inadmissibility to him that your future husband would have to file on your behalf if you are unable to adjust status in the US.
Behar Intl. Counsel 619.234.5962 Kindly be advised that the answer above is only general in nature cannot be construed as legal advice, given that not enough facts are known. It is your responsibility to retain a lawyer to analyze the facts specific to your particular situation in order to give you specific advice. Specific answers will require cognizance of all pertinent facts about your case. Any answers offered on Avvo are of a general nature only, and are not meant to create an attorney-client relationship.