They're only $445 new. I'd sell it at $400 and hope for the best. Sell the other stuff separate. The good thing that you have going for you is that they are hard to find. Buds just received some last week and they're sold out again.
On a side note, I just picked one up. Rock Island has awesome customer service. The previous owner buggered a few things up and I called to get the right part numbers. They sent out the parts under warranty despite the fact that I clearly stated that I was the second owner and that obviously a drunken monkey with a tool set was the cause of the malfunctions. I was like "No, seriously...take my credit card number, this isn't Armscor's fault."
Customer service so good that I felt dirty and like I took advantage of them.
$445 is an excellent price, and if you can find one new at that price I would suggest getting it. I would consider getting another at that price, if the fun money account were a little more stocked.
Now if we're talking used, you can find some better deals. I bought one here off the forum with 3 mags(1 ACT, 1 Wilson, 1 Colt), Hogue grips, and a few rounds of .45 for $400. That was a good deal as it has become harder and harder to come across a good condition RIA GI much less a Tactical, and the GIs are going for right around $400, which is close to list price. If he's going to sell as is, I wouldn't start out a penny less than $450, but would probably start at $475. You may take a little less but you at least have a starting point to begin.
As far as RIA customer service, you are spot on. I had previously bought a High Standard/Armscor 1911 that was an absolute joy to shoot. Worst mistake I made was selling it. I finally located a Rock Island Tactical 1911 that I purchased. The pistol I bought was practically new so I called about correcting a couple issues, hoping for a replacement part, and they all but begged me to send it in and let them go through it. After a few weeks I get a call that there is a more serious defect and the gun needs to be replaced. I agreed and they threw in their customary extras. The gun I received back was much tighter and I look forward to shooting it, a bunch. I would not hesitate in any way to buy a Rock Island firearm.