Its been a total headache trying to figure out how to get from NYC to AC by bus that I thought I should share my findings.
Academy bus: it no longer runs to AC
Greyhound: they have a casino deal but there is no information on their website that is of any help (I called and tried the web chat: also no help). The website says to order a ticket with the casino as the destination instead of AC. I did this, it was $49 rt and the casino refused to give me a casino voucher on arrival ($25 slot play). The casino bus attendant explained that you need to order tickets in cash at the terminal in order to get the voucher. Amazingly the casino knew more than the bus company. it's first come first serve and $45 I believe.
You can get the times from the greyhound website by plugging in the casino as your destination. do not book online though if you want the free slot play.
Chinatown bus: there's a Chinatown bus with a regular schedule serving ballys Caesars and harrahs. they have a small desk at the casino terminal. I haven't taken it yet, but was told it's $27 RT with a $25 slot voucher and $50 match play for table games.
this picks up from Confucius plaza (9 chatham sq.) in Manhattan as well as a location in flushing and Brooklyn. The name is in Chinese so I don't what the company is, but their number is 212-966-8433
buses depart Chinatown at:
Both greyhound and Chinatown buses have an open return, so you can take any bus back. Also since they are first come first serve, its best to arrive early to avoid it selling out.