to answer your question, one would need to know if you intend to use this coop as your primary residence or a pied a terre. You mentioned that you are not a US resident, which means that you spend less than 180 days in the country, unless you meant that you work here full time on a work visa and do not have a permanent residency. If you are not going to use it as a primary residence, you would have to find a coop that allows pied a terre (buying as a second home). Also, if you would like to rent out the apartment later on, some coops have very limiting sublet policies(for example, have to use the apartment for 2 years and then can rent 2 out 5 years). However, some coops have more liberal rules and you have to look hard to find the right one. Coops also have a number of financial requirements post-closing - to have 2-3 years of mortgage and maintenance payments in liquid assets and debt + maintenance payments not to exceed 30% of income.
Another important question would be financing. If you intend to finance your purchase and are looking to get a loan in the US, as a non resident, you would have to put 40-50% down and expect a 3-4 month process. If you have a permanent job in the States, it may make things a little easier. I work with a mortgage broker who has loan programs for non-residents.
I would be happy to discuss all related issues and help you find the right place.
646 593 7207