www.leatherwoodoptics.com/

The link posted above is for a "newer" Leatherwood company.  Don't know much about their scopes other than the ads.  From the photo on their site, their scope is trendy with its large objective.
 
There's a couple of other options.  A company called DMPS located in Becker MN makes the ART II scope.  It is similar to the VN -era ART.  Looks about like it and is built pretty well.  You have the choice of having this scope attach to the rifle with their "government" mount, or you can get the scope with rings to attach to your mount.  Price is about $750 retail.
 
If you're looking for a VN-era ART, you might try over on Culver's Shooting Page and put a WTB ad there.  About four years or so ago, the CMP was selling beater ART scopes from government surplus.  Some arrived at the above place in Becker for fixing.  That place was real slow on repairs for quite a while.

No one likes ebay but thats were I found mine.  Its a classic.

A friend of mine at Ft. Campbell has 2. He was thinking of getting rid of one of them. I'll give him a ring and see what's up with it.

Good info in Plaster's The Ultimate Sniper book on the ART I and ART II.

THERE was an original ART scope for sale in the EE a week or so ago, i here the new ART scopes are crap ?
there is one for sale on gunsamerica as well.original ART scope.

good luck

thats one of two i have seen for sale both in the $1200.00 range .
try this link for the new version and pruce
http://www.amerisurp.net/scopes_lw_sporter.htmwww.amerisurp.net/scopes_lw_sporter.htm