Who makes a budget single shot break barrel 45 acp, if any? Anyone make a 45acp barrel to put on my H&R?

Not sure if anybody makes a barrel for the HR but if you have a 12 gauge break barrel you can get a Short Lane adapter for it.

http://www.gunadapters.com

No one. I have been looking for years.  I have a .45 supressor and a gun like you describe would be wicked handy at 16" and suppressed.  Even handier SBR'd...
An alternative would be .45 LC - the can would work anyway.

There are/were .45ACP Contender barrels.

http://www.midwayusa.com/product/697001/thompson-center-barrel-thompson-center-contender-g2-contender-45-acp-1-in-16-twist-14-stainless-steel

Bullberry still makes them

http://www.bullberry.com/contender_barrels.html

I DO NOT mind being wrong  But the first one is discontinued - I knew about that.  The second option is really a "how BAD do you want it?" sort of question.  $300 for the barrel and another $115 to thread the muzzle end.  Damn.  But thanks for the link.

They make a pretty nifty package, suppressed and SBR'd.  You can find deals on used Contenders, in the H&R price range.  Often sell the barrel that comes with it to recoup some of the initial cost as well.  

I'm not sure what the "ideal" barrel length is.  On suppressed Contender pistols or the SBR, I've gone with barrels in 4", 6", 10", plus the rifle length stuff.  




And another option is a .44 Mag barrel, shooting .44 Spl.

I just took a tour of the offerings on gunbroker - 15 pages worth of Contenders, barrels, etc.  Lots of .44 mag barrels.  I already reload .44 Spl and .44 Magnum.  You have me thinking.

Not what you asked, but regarding single-shots & suppressors wanted to toss out an idea to avoid another tax stamp. I went a maybe unusual route with one of mine, getting a single-shot .357 mag H&R shortened to 16 1/4" & threaded for my 9mm abraxas suppressor. Looks odd without the suppressor in place, but still works fine (it's VERY fast-swinging in the brush), and it eliminates one of the $200 tax stamps that would otherwise be necessary:



With suppressor attached, it's actually fairly stealthy visually; it looks almost like a regular carbine (then you pull the trigger and people wonder what kind of pellet-gun you're shooting ):