Unfortunately I cannot buy off of gun broker. I had an account years ago in which I bought one gun for. Since then I have tried to make a new account and Gunbroker wont allow me to for some reason. They also wont get back with me on how to delete the other account seeing as how it is with an old work email I no longer have access to.If its an older Agent, then it will be blued, unlike the newer one from the mid-80's which would be parkerized. Since he mentioned that this one didn't have the underlug it would probably be a second generation Colt, depending on finish the price is about right for that model. If it was me I would look for a regular Detective Special. I've never been fond of light weight framed snub nosed revolvers. It does happen, and the light weight frames will crack, and usually do under the area of the forcing cone. Since most light weight frames are made from aluminum there is no way to repair it.
Besides the OP could go over on www.gunbroker.com and find several Detective Special's (all steel) for the same money as he's looking to pay for the Agent.
http://www.gunbroker.com/item/584170927
http://www.gunbroker.com/item/585469394
http://www.gunbroker.com/item/585186944