Air Conditioning - Compressor woes

Today I got a call from my wife that the ac is not blowing cool air. I came home early and used the little experience I've gathered from this site to troubleshoot. I noticed that the condensor fan was working but the compressor was not kicking in. I opened the side cover hoping I will see something obvious on the capacitor and contactor but they "looked" clean. I could see clearly (and hear) the contactor kicking in as my wife turned on the ac from the thermostat, so I am assuming the capacitor is ok. I didn't have a tester, but knew that my neighbor did; so I asked him to check it for me. I am getting about 27 volts on the coil side of the contactor and, according to him, the other connections on the contactor(t1, t2, etc?) were within range. My neighbor, who works on ac at his job and is certified claims that the compressor is stuck and suggested replacing the entire unit. Does that sound right? I told him that my research from this site tells me that I should replace the contactor, but he insisted that the contactor is ok. Any comments appreciated before I make this big and expensive move. Needless to say I live in hot South Florida. Prior to this, the only thing I've noticed about the compressor was that it was making a startling loud noise for the first two or three seconds and then it would settle down to a softer tone. It's a Goodman 2-ton unit.

edit: ok, so I convinced him to replace the contactor. He had a brand new one on hand so I didn't have to purchase one. He was right about the contactor not being the problem for the new one didn't make any difference. I guess I will be replacing the entire unit, unless anyone have any ideas. Thanks.

After the fan spins for about 20 seconds, I hear a faint buzzing sound like it's the compressor trying to kick on but then it dies immediately. Does this mean it's stuck? Is there a way to free it, or should I stay with the course to have the entire outside unit replaced?

You know if this had a start capcitor on it? if you have a TXV valve inside the house, it should have a start capcaitor to give it a "kick" to run..

some time it just needs a kick to get started.. may have to call in a pro to see if they can do it..