I'm lookin at purchasing my 1st .50 cal and was wondering what are your thoughts on Ultimate Accuracy International's  Iver Johnson/AMAC Model 5100. What is generally the going price for one of these puppies? Thanks.

The first thing you should do is join the Fifty Caliber Shooters Association (fcsa.org) in order to get access to their members forum and vendor list.  It costs $40/year, but is money well spent and will be paid back many times over.  You will have access to the top shooters and experts in the 50 caliber world, and included is a subscription to their printed magazine, "Very High Power", but even without the magazine it would be worthwhile.  I joined just last week and have already spoken to one of the top shooters and world record holders, and got very good advice on building a benchrest gun.

Leave out the "international" or you are going to confuse yourself and others.   The Accuracy International rifles and the Ultimate Accuracy AMAC are two different beasts.
I was planning on buyig one of these for my first .50.   The only thing I don't like about it is the weight.   I have looked at one close up and they seem to be quality built.   They are usually priced at about $3300 new.   Your best bet is probably www.klomont.com.   I think he had a deal awhile back where there was some match ammo included but don't see that advertised anymore.
Anyhow, I had my mind set on the AMAC until I saw an AR-50 at a gun show, had to have one and it was cheaper.   I don't regret my decision since I love my AR but I would still like to have an AMAC if I could afford another .50.
The AMAC does come with a scope mount and rings and bipod so all you need is a scope and you're ready to go.   But for $700 or so less for the AR-50 you can easily get that covered.

Rokchukrslave,
Yeah the AMAC was my first choice also, that is until I saw the AR-50. Both are built like tanks and are fine rifles, here's the diiference for you Tac45.

The AMAC is a "shellholder" design, which means that you pull the entire bolt out of the gun to load a round onto the bolt and then reinsert it. Some people don't like the design and in the past there have been a couple "incidents" with the shellholder design but these were traced back to the owner. Simple fact, don't mess with the design if you don't know what you're doing and even then it's not a good idea. You can order it right from the factory ultimateaccuracyarms.com

The AR-50 is a traditional bolt gun with many accessories available for it. I shoot with Darin a.k.a Prince50 who makes all the accessories for Armalite, they are the best on the market period! You can also swap out the factory trigger group if you don't like it as it uses a Rem. 700 style trigger. I think they now offer a match chamber for the AR-50 if you ask.

Diddo here too! I am going to buy a ar50. However I asked a month ago about the chamber with armalite and a dealer and was told they were all milspec chamber for surplus use,not match. I never did get a answer about if able to get it in match just told all were milspec. I read elswhere today that said same thing can get it eitherway. I personally want match since I plan on loading my own anyway but would like to shoot surplus which most say won't fit spec wise. I want the accuracy anyway. If I can get one match chambered then thats the way I will go. I do know some take the long lead setup the milspec has in it and rechamber it make more of a match chamber for there handloads and will be more accurate but also sure the chamber still is oversized like milspec rather then tight match chamber like also. Right now looking at a month and i should be able to rder one hopefully someone will have some lefties cheaper than Knesek in stock since everyone else it out of stock that are cheaper then Knesek.

Don't sweat the ordnance chamber, it is fine.   My best group so far is 5 rounds in 1 3/8" at 300yds and I have also shot a 2 3/4"  5-rounder at 550yds.
If this is your first .50 then you will find out that technique will get you far better results than worrying about having a match chamber.