I have a great guy, has done a lot of work for me, large paver patio, gigantic flight of steps, gave me a quote for replacing a 10 foot high, by 40 foot long retaining wall, including removing the existing wall (railroad ties) at IIRC $35 per square foot. I have no idea what competitive pricing is in Suffolk County. I'm in Melville, he works all over the island, and is based out east.

Let me know if you still want the number, I see your post is already two weeks past.