The cost for a K-1 visa can range from $1,000 to $5,000 including government fees, medical exam, and legal assistance.

Basic K1 Visa Cost Overview

Government Fees Variable Costs
USCIS Filing Fee: $675 Travel Costs
Embassy Fee: $265 Medical Exam (Varies by country.)
Total Government fees: $800 Assistance (ie. RapidVisa or an attorney)

K1 Visa Costs & Fees Breakdown

USCIS Filing Fee - $675 This is the fee required to get started with your petition. It goes along with Form I-129F in the initial filing of the K-1 visa petition.
Embassy Fee - $265 This fee is paid towards the end of the process, payable directly to the U.S. embassy where your fiance visa interview is conducted.
Medical Exam - $100-$500 This cost varies based on the country for your interview. It is paid directly to a medical facility determined by the U.S. Consulate.
Travel Expenses - (Varies) The cost for the foreign fiancé to travel to the U.S. after the visa, along with any travel the sponsor does can vary from a few hundred to tens of thousands of dollars. Also consider if the foreign fiance is not from the city where the consulate interview will take place, there will be more travel.
Assistance - (Varies) Lawyers can average from around $1,800 to about $3,000 for a straightforward case. RapidVisa's assistance starts at $629 and has payment plans starting at $159 per month. Other agencies charge around $800-1,400.

Other costs you should consider are:

Postage - Getting files back and forth between you, your fiance, your agency/attorney, and the government at various steps. If your attorney or agency uses secure document transfer, it can save time and money.

Cost of Acquiring Certain Evidence - Hunting down old divorce decrees, bank statements, or birth certificates can add to the tally.

Passport - If the foreign partner doesn't already have a passport, he or she will need to acquire one.

Passport Photos - Passport photos are required for the K1 visa. Make sure the foreign partner gets them in the right size and standards.

Children - There is no extra USCIS fee if the child K2 applicant accompanies the K1 applicant, however, there will be additional embassy and medical exam fees.

Translation Service - If you need certain documents translated, and don't have a friend to do it for you, this could add to your cost.