Need advice immediately on sale of item?

I posted a fairly expensive item ($700) on Craigslist and got a taker right away. He wants to send me a certified check and then make arrangements for pickup when it clears. Is this usual? I am balking at the idea of sending him my name, address, and phone, even though I would do that if he were coming to pick them up today.

His first message was under one name and his second (by gmail) was under another.

Anything about this sound off to you? I’m not an experienced seller and don’t know what might be routine and what’s not.

Thanks—need to know quick.