First off, where do you get off saying that I get "caught up" in the whole made in the USA thing? I like things made in the USA, they are generally very good to top quality, but not a guaranty. I also like products made in Canada, Germany, Italy, France and other countries, also typically good to great quality, but no certainty of it.
Right...you didn't specify USA...my bad... that said you're complaining of a pump IR is using with absolutely zero experience with it.
Moreover going on "i heard" will get you chasing your tail in a race with no other runners. It's like hearing Billy Joe Jim Bob Danny Frank say don't use ___ oil ...it will blow your motor up because frank who is cousins with vinny has a neighbor who heard his cousin blew is v8 up running that oil 

I have also had my fair share of arguments that made in China, is not necessarily ****. In fact, They are a leading nation globally in electronics, nuclear power, advanced space program among other things. What we get imported is usually (but not always) ****, because that is what we want. The market wants the most for the least, which in turn forces companies to setup shop wherever there is cheap labor, to import back to us the cheapest price possible.
That's a topic I don't have the time to get into on the why. I could explain in about a full hour the problem..
So, I never said that it has to be made in the USA. I have read on this forum as well as many others, that IR has been for many years making "****" for their lower entry level models, to grab more of the Campbell Hausfeld, Harbor Freight, and other cheaper brands that I have no idea what the numbers are, but suspect the entry level stuff has a large portion of the market.
What you have there is label shock. It happens every single time a company known to have xyz COO all of a sudden starts using a part(s) from a lesser known place.
Think Milwaukee tools. People went ape **** when they started seeing Made in China on those labels. You know...how dare they!!!
Can I say that the Chinese Milwaukee grinder is inferior to it's earlier USA made version?
When they both keep working like they should how do you quantify such a thing then?
If you go off "i heard" and people pissed off they aren't USA made now...well then they'd never sell another tool. Truth is they sell them everyday and if the Chinese variety was that inferior to the USA version it wouldn't take long for people to flick their nose at them.
If it is true that they make them cheaper, it does not mean they are all lemons, or any are really lemons. Maybe they won't go 20-40 years like what they used to make is the difference.
Your IR is doing well, good for you.
I don't have a personal love for IR or Tractor Supply but that model I showed you as example has 865 reviews on their site with an average score of 4.5 out of 5.
Factor in that there are some real clowns out there who don't know how to set things up...or neglect maintenance...
That's a pretty ******** remarkable score .... 4.5 of 5.0 from 865 reviews.
I read on another thread that Quincy was following IR's lead, (I would suspect because IR maybe has had a slight uptick in market share) probably because they also want to grab some of the low end market.
Again...if they're outsourcing a part (to their specs) to be competitve at a price point...and it works well for the duration with proper maintenance...so what. If it's truly junk(not sour grapes) ...it won't take long and their rep will be forever tarnished to a door closing level.
Is it any different than BMW, Audi, Mercedes, all introduce these lower model lines that did not exist 20 years ago. Or when someone sees someone driving an A3, they make a comment to their buddy...."it's basically a Volkswagen but they stick some Audi badges on it, charge a couple of $$$ more, and the smuck gets to say he has an Audi.
I've been in the auto business, repair, sales, dealership front and back, F&I... for nearly 30 years.
My response is...H U H?
These "lower" model lines have been around longer than 20 years.
Moreover they aaren't "lower" model lines.
The automobile "class" segment has driven this. 45 years ago what did you see? Big cars and some trucks. I say "some" because not many trucks back then. Nope. Forward to present and the 1/2 ton truck dominates the sales world. They are everywhere. What else do you see? Mid size cars, SUV's, compacts, CUV's, what's rare is now the big car.
Moreover an Audi is a VW but the Audi is nicer. Been that way for...ever. Lincoln was a Ford..but nicer. Cadillac a GM...but a nice one.
It would financial suicide to have all their very own exclusive parts, engines, transmissions, etc.
Audi does use some exclusive engines in their models where a VW doesn't exist. Like in the super cars. Bugatti has their own as well...but both under the VW flag.
I am not a know-it-all and typically seek advice and opinions, like on forums like this.
All my cynicism aside, I am looking for used, hoping for $600 or less, and wanting to avoid models that from what I have read, are being made cheaper in recent years.
I can't help you with a $600 tag but I can tell you my experience and for further reading 865 reviews of a particular model that you "read" someplace as a "cheaper" product with an average score of 4.5 of 5.0 ...again with 865 reviews.
P.s.
I didn't review it. That is not my thing. If I did I'd give it a 5.0
Good luck in your endeavor.