As a recently retired realtor, life long Westchester resident and VP of my coop building, the bottom line issue is the financial picture of the coop building itself. I know for example, the monthly maintenance fees at 177 E. Hartsdale Ave. (at Rockledge Rd.) have always been very expensive. There is nothing special about the building that makes the monthly fees so expensive. I know of coops with 24 hr. concierge that have lower maintenance fees. This is why I question that coop building's finances. The neighborhood is not as wealthy as Scarsdale, Larchmont or Rye, yet coops in those 3 wealthy towns have lower maintenance fees. The difference is the selling prices for coops in Scarsdale, Larchmont and Rye is much more expensive than Hartsdale.
Unfortunately, you are not allowed to see a coop's finances until you have a signed contract. Typically, your lender and/or attorney will review the coop's finances on your behalf. As for making a decision, I would go with a high cost low maintenance coop PROVIDED the coop is located in a better neighborhood than Hartsdale. If you are tight with your budget, you will be limited and might be forced to stick with Hartsdale.
Since it looks like you have not submitted an offer yet, have you looked at coops in Larchmont, New Rochelle, White Plains, Eastchester and Mamaroneck? These are all nice neighborhoods and I know of coops with affordable maintenance fees and reasonable asking prices. Look at coops on Palmer Ave. in New Rochelle / Larchmont / Mamaroneck. Also White Plains - North Broadway / Lake St. / Franklin Ave.;
Hoping you are pre approved as I know realtors will not take you to private showings without a pre approval or proof of funds. By the way, my coop is on Palmer Ave.