For most New Yorkers, a good relationship with a doorman isn’t just desirable, it’s necessary. It costs a pretty penny to foster that relationship, too.

Doormen wield a great deal of power. They know who your visitors are, where your packages are coming from and they may have even seen the stains on your clothes that were picked up by the dry cleaner. They’ve mentally cataloged some of the most intimate details of your life — along with details of all your neighbors’ lives.

“At first I found it really annoying,” said Bennett Dubson, a 45-year-old general contractor who has lived in a doorman building for the past 13 years. “I’m a grown man, and to have other grown men open the door for me and nose around my business seemed weird. Over the years, though, I came to think of them as friends.”

They’re very expensive friends, and they are getting more expensive. Assuming a building has a 24-hour doorman, it requires at least 4.2 full-time doormen for 168-hour coverage.

“Each doorman costs approximately $40,000 a year, so a building with a 24-hour doorman will add expenses to the tune of $166,000 a year,” said Ronald Tradanico, executive vice president and sales manager of Bellmarc Realty. “If that’s divided by 300 tenants, the price is relatively low. But if you’re splitting that up between 50 tenants, that’s high. The upside is that you have a wider audience to sell to if you live in a doorman building. Nobody ever says, ‘I absolutely will not live in a doorman building’.”

In addition to the $1,000-plus monthly maintenance fees New Yorkers may pay for doormen, end-of-year gifts could potentially add up to thousands of dollars, depending on the building and the number of employees.

There isn’t a set rule about how much to give at the end of the year, so for tenants in those buildings, anxiety surrounding annual gifts typically starts in mid-December when building employees may send out a card or a chart that includes their names, their responsibilities, and maybe even a photo to help identify them.

“I may be cheap, I have no idea, but I probably give $100 to the top-notch guys, and $30 to the guys I never see. You have the proclivity to give generously because they work where you live — you see them everyday, so you may overdo it out of fear. And they’re total weasels; they’re much more responsive in the fall months before you pay them,” said David, a 32 year-old sales executive on the Upper East Side. He declined to give his last name for fear of retribution.

It’s precisely this fear that may help doormen land better gifts than they justly deserve.

“Sometimes I may have tipped more than I might have wanted to because I know how everyone talks,” Mr. Dubson said.

In general, according to several doormen, the tenants with the most scandalous secrets tend not to give as liberally as well as absentee tenants.

“You’d be surprised,” said Asip Bal, a 25 year-old doorman from Queens, who works in a downtown building. “It’s the guys who bust your chops all day who give you $5 at the end of the year. The guys you never see, the easiest guys, might give you $200. I never try to cozy up with tenants before the end of the year because it’s pointless. You work with these people all year. They know you.”

Although there’s no hard data on the subject, anecdotally, both tenants and doormen say the average end-of-year gift is climbing slightly. Mr. Bal estimates he received about $5,000 in tips last year, and between 10% to 15% less the year before.

“About 30% of tenants have increased how much they give,” Mr. Bal said.

David estimates he collectively spent roughly $3,000 on year-end gifts for about 40 building employees last year, including the superintendent and maintenance staff. For the doormen he was particularly grateful to, he added another $5 to $10 per person from the previous year.

“If the service is good, I’m willing to pay more. But I used to live in a building where the doormen wouldn’t do anything, and they couldn’t have cared less. I hated having to tip them.”

Still, despite the rising costs of doormen service, one broker says buyers have yet to be deterred by maintenance fees — even in a softening real estate market.

“People fall in love with apartments and basically that’s why they buy them,” said Lenore Silverstein, a broker with Coldwell Banker Hunt Kennedy. “Unless the maintenance fee is outrageous, it’s not going to have much of an impact on an apartment’s marketability.”