here are some great listings for AK's plenty of options.. id go buy the nhm for the barrel nut that has perfect threads underneath.. especially at this price of 419...
nice NHM 90 419$
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=382874091
Mak 90 650$
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=382796266
mak 90 600$
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=382634364
Mak90 555$
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=382297508
Mak 90 600$ clean
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=381718059
nice NHM 90 419$
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=382874091
Mak 90 650$
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=382796266
mak 90 600$
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=382634364
Mak90 555$
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=382297508
Mak 90 600$ clean
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=381718059