I would like an ar with a barrel shorter than 16".  Is it possible to put a short barrel upper with no bayonette lug and flash suppressor on a post ban lower if I register it as a SBR?  Where would I start looking for an upper?  Also would I be able to have the barrel threaded for a silencer in the future?

yes u can reg a post ban as a sbr as long as the gun still complyus with the 94 crime bill. u cant have a silencer on a post ban becouse atf consideres it to also be a flash hider

So there is no way to put a silencer on the AR unless its pre-ban?

Quoted: yes u can reg a post ban as a sbr as long as the gun still complyus with the 94 crime bill. u cant have a silencer on a post ban becouse atf consideres it to also be a flash hider

If you register it as a SBR it is NFA FIREARM and the crime bill DOESN'T INCLUDE NFA FIREARMS.  IF I read the law correctly.  Contact the ATF to be sure.

If it's a post ban it still can't have the evil features.  My Form 1 in the "Approved" box statesWith the following conditions, if any: The manufacture, transfer, and possession of semiautomatic assault weapons must be in compliance with 18 USC 922(v).

as far as i understand it...

if it is a MACHINE GUN then the pre/post ban deal doesnt apply because it no longer falls under the "semi-automatic" clause.  since the SBR is still semi all rules, however stupid, apply

Quoted: So there is no way to put a silencer on the AR unless its pre-ban?

Correct. Even though a SBR is an NFA item, the R in SBR still means it's a rifle and subject to all the post-ban rifle limitations.

Machine guns aren't considered rifles because they can fire more than once with a single pull of the trigger.

What is the current price for the SBR "stamp"? $200/00?

Quoted: What is the current price for the SBR "stamp"? $200/00?

$200.00 is correct.

"I would like an ar with a barrel shorter than 16".

Check your state laws.

"Is it possible to put a short barrel upper with no bayonette lug and flash suppressor on a post ban lower if I register it as a SBR?"

No.

"Where would I start looking for an upper?"

Just about all of the AR15 manufacturers make some sort of a SBR upper.

"Also would I be able to have the barrel threaded for a silencer in the future?"

Post-ban = No.

You could take a post-ban AR15 and register it as a SBR (state laws allowing) and then install some sort of a non-threaded silencer on it and register it.
Of course you would have to pay for two tax stamps, one for the SBR and one for the silencer.

USNJoe see cyrax777's post above.  The only way you could put a suppressor on a post-ban is to get rid of the pistol grip.