Like any new hobby—golf, fly fishing, archery— you need to dip your toe in the water to see if you like it. That normally means borrowing equipment, then buying less expensive items to see if you will like it. For me it was a used Benjamin M-Rod in .25. I had competed with a FWB 300S against Mike Anti (I lost, BTW) and knew that I loved air rifles. Fast forward 25 years, I had no idea that the modern PCP air rifles were to accurate and so capable. I have since sold that M-Rod and moved up to FX and Daystate and am quite content with their fit, finish and performance. If you buy a used, well-cared for piece, you are essentially “storing” money. I have practiced that line in front of the mirror enough to not snicker when I deliver that excuse to my wife. If you tire of it, like Craigslist, you put it back in “the cloud” and let someone else enjoy it. You may be out, at most, a couple hundred bucks. In the grand scheme of things, its nothing.
So your initial question: Are high end air rifles worth the cost? I’d say, “Yes.” If you have to buy used, so be it. The utils of satisfaction will offset the money saved by buying a lesser gun.
What is the best gun you ask? Well, like what is the best wine, a cigar or a fly rod....the best is... your choice. You will come to that answer after experimenting with different guns and coming up with which one fits your needs and budget. There are many wonderful choices out there and there are no wrong answers.
My kids and neighbors and I have spent countless hours shooting flies and having contests. When the equipment is capable of hitting mosquitoes at 50 feet, when you miss, you know its the shooter, not the gun.
Enjoy the ride. I sure have.