Is it worth 4 or 5 others?
Of course it...can be...sometimes...
There are two wrong ways IMO to look at it, to say "in general no" or to say "in general, yes." I say this because that decision should be made on a case by case basis, using an open minded perspective each time. I've trade multiples for one, and I never regeretted it. It all depends.
I think early on, gun collectors and shooters make the same mistake - that having quantity is special, and while it can be, quality is that much more special. Having a codensed collection of special pieces, but less of them, is always better in the end. That is why I have often said a 200 gun collection does not impress me, unless its 200 quality pieces. Having 200 guns, which are cheap and or common is something that a lot of people could do, if they wanted it. Many of us may have a large mortgage, have another hobby (or addiction), a car payment, etc that prevents us from having 200 guns. Sometimes we choose not to have that many, but the point is, having a large collection is attainable for most people, IMO.
That brings me to my next point: How do we each look at our guns? I often look at a gun valued at $200 as "$200" which works for me. Others view the gun as a grown up toy, others a connection to past time in their life, others see guns from loved ones and remember that person. In reality, we all probably have guns from each category. I however, usually assign a dollar value to the gun (unless its from a family member). If I have for example 6 Winchester 94s from the 70s, all in 30-30, valued at $400 each, and I can trade them for a $3000 gun, I will do it each and every time. Having a ton of common guns isn't all that impressive in my mind. The bigger consideration is the total dollar amount for each side, rather than the total amount of guns, IMO. I mean who wouldn't trade 4 common Glocks for a vintage mint boxed SIG P210, for example?
However, there are some guns we all have which we would hate to do without for various reasons. I have some I would be reluctant to trade but when the trade results in $500 for my $300 gun, I am often very interested in that trade. Sometimes a trade is even dollar wise, but still worth doing because maybe the gun you are giving up is a tough one to sell (if you were trying to sell it) or maybe you are getting a much more prized gun, despite the money being close.
The way I do things, probably closely patterns the way bluestarlizzard's dad did trading, buying and selling to get his collection. I'm a collector at heart, but I don't ignore the money either. By either buying or selling the wrong way, many of us make this already expensive hobby more expensive than it has to be.
I snapped a photo of a prime example of when I personally would trade several guns that I have, for one.
Below is my collection of S&W 1st model revolvers. There were 3 issues of the 1st model: 1st issue (top), 2nd issue (right) and 3rd issue (left). First issue guns are hard to find. They were all made before the civil war, which probably increased their attrition rate. Many 2nd issues were made during the civil war but most were not, and for the 3rd issues, all were made after the civil war. In addition, far fewer 1st issues were made compared to 2nd or 3rd issues. There were over
All guns work in the photo, and the conditions are above average (except for maybe the gun bottom left). On the left there is an all blued 3rd (scarce) and another 3rd that probably shipped with the pearls it has. The bottom gun on right, a 2nd issue, has nearly all of its silver plate on the frame (barrels and cylinders were blue, frames silver plate for 2nds), so the condition is great. Despite all of that, I would trade the 6 bottom guns (3 on left and 3 on right) for the top one, just about every time. To a S&W collector, a so called 1st model 1st issue (aka 1st 1st) is a big deal. Mine happens to be a 3rd type (there were 6 sub types of the 1st issue) which is more scarce than the later types 4, 5 and 6). Most seen today are type 6.
I have many other guns that I would trade multiples to get, because they are scarce/rare, historically significant, more valuable, and often more special to me.
Months back, a seller on gunbroker was selling a collection of approx 50 S&Ws from the same guy. I believe he was a retired dentist, IIRC. Many S&W collectors have over 50 S&Ws, so I wondered how great of a collection it was, in the scheme of things. Then I started looking at the guns. Every gun he had was either rare, factory custom, all were vintage, many were lettered and most were in very high condition. Some of the more special ones (all were special) were a 6in registered magnum, ANIB and a triple lock target (scarce) in 44-40 (rare) which had 2 extra cylinders fitted to the gun, and numbered to it from the factory, one in 44 Russian and one in 44 special. IIRC the Reg Mag went for around $12k and the 44-40 went for $7.5k. Despite being "only" 50 guns, that was one great collection. In my collecting, I have attempted to focus more in on having better guns than having many lesser firearms.
I'm also not ragging anyone who really enjoys having a large arsenal, or having 9 different 10/22s or 15 AK47s. I am just attempting to point out a different philosophy regarding firearms acquisition. Early on, I had many examples of guns which would not interest me today. OVer time, I slowly refined what I look for, which means I pass up many guns. In the long run, I think I am better off than I used to be. Being selective during purchasing can reap big rewards when selling, if one decides to sell.