They provide permanent cash flow but seldom are the main source of income. Either it's a group romantic tour with socials, or an individual tour, the agency has a fair piece of it.
Gift delivery, translation and email forwarding services offered by a Western based agency are more expensive, and less flexible than the ones provided by a local agency.
Western agencies usually start by placing ads in local Russian newspapers that promise to help women in search of a partner abroad. Usually a lady will send applications to 5-15 agencies that placed ads in the same newspaper.
When an agency has enough profiles to start from, they launch a website, and offer the women's information to men.
If later the agency phones asking them to fetch their letters, they may come, or may not, or come in a month time - depending if their way will be somewhere close by during the agency's office hours.