Purchase and Arizona State will give student ID cards to their older residents, and say they are working out the details of how much access to campus amenities the residents will be offered.

At Purchase, residents and students will take short courses together, because research has shown that most retirees had little interest in full-length courses. And a student performance space is being built within the retirement complex.

The New York Legislature approved the long-term lease of state land for the project in 2011, and Purchase College set up a nonprofit organization to develop it with a private operator, at a projected cost of $320 million. Officials are expecting a base of $2 million in annual rental income, to be used to almost double the college’s $1.8 million scholarship fund and to hire new faculty members.

At a recent marketing session for the Purchase project, called Broadview Senior Living, Ashley Wade, the project’s marketing director, gave a hard sell to about 25 potential buyers.

“You don’t have to go to class,” Ms. Wade said. “You just get to go to class.”

Many of the listeners were in sticker shock. The Purchase College “entrance fee” ranges from $595,000 for an apartment to $1,995,000 for a small house; monthly services fees range from $4,300 to $8,700 for one resident and $1,500 more for a second person. When the unit is vacated, 90 percent of the entrance fee is refundable to the residents or their heirs. One-fifth of the units are reserved for people with incomes at or below 80 percent of the median income for Westchester County; for them, the entrance fees start at $250,000.

Prices at Arizona State’s project, called Mirabella, range from the mid-$300,000s to more than $1 million for a penthouse apartment.

Judy Cohen, 82, a retired English teacher, and her husband, Martin, 84, a cardiologist, wondered whether they would be welcomed by the students.

“The students have their own life,” Dr. Cohen said. “I don’t know how many would want to come and sit with. …” As his voice trailed off, his wife picked up the thread: “Old people,” she said. “Let’s put the word out there.”