Unfortunately the questions you are asking would take me an hour to try and explain well. You are correct in the couple things you mentioned as part of the equation for why the difference in price. Something that will help as far as visibility goes is to look at this relative brightness calculator that can compare different wavelengths and power:
Relative Laser Beam Brightness Calculator: (532nm 100mw) vs. (445nm 1007.49mw)
For instance, if you put in 532 and 100 and then put in 445 and ? and push enter it will tell you how much 445 you would need to be the equivalent brightness of 100mW of 532nm which is just over 100mW for the beam. If you then select dot instead and enter (actually calculate) you can see that the dot of the 532nm will actually be twice as bright even though the beam is the same.
A 405nm is much more difficult for your eyes to see and if you still use 100mW for it and have it calculate for 405nm beam you would need more than 6W of 405 for beam and 19W for dot.
Unfortunately the strongest 405nm is just over 1W (1000mW) and a 1W 405nm beam is as bright as 5mW of 532nm.
However, the beam width (or what we call divergence) of a 405nm is really small so it has a very high beam density so there's a lot of power in it. It's kind of like saying if you were letting water come out of your garden hose and it hit you it wouldn't hurt but if you forced that same amount of water out of a straw it might hurt pretty bad. It's why a 405nm burns really well. You could press a nail again your hand pretty hard before it would puncture but try that same pressure with a pin and see what happens.
Power for power of the common diode wavelengths nothing burns like a 405nm. Power for power of common diodes nothing compares to the brightness of a 532nm. Try putting in 520nm (anot her green that most of us like the color of over a 532nm although it will generally look the same unless shown side by side with the 532nm) and a 638nm (red) to see how they compare.
What you need to know though in general to better compare things is the diodes divergence, brightness, cost, availability, wavelength and how how much power you can get with the wavelength for the $ you are willing to spend. What is most important to you such as visibility or burning and then other things like what kind of host you want it in and how long do you want to be able to keep it on before it has to cool down and do you like small medium or large hosts.
This is why if you get interested one laser will just not be enough and you find yourself collecting a lot of different wavelengths with different hosts and battery sizes and chargers and owning your own LPM (laser power meter) and building your own.
You get the gyst why when someone asks questions like you are it's hard to answer because there is so many parameters to consider. What you are asking has been asked a 1000 times before and there's just no simple way to do it just like I can't directly tell you if that 1W blue is really good or not and unless someone has read this thread and owns it you won't get an answer to that question. There's a huge number of sellers and it's very common that a specific unit someone may ask about has no personal answers for it.
I gave the links to O-like because they have some great bargains and the units I've purchased were worth the $. There are far better sellers but with high quality comes high price. It's up to you whether to take the chance or not that you will get a decent unit.
Everyone who comes here wants to buy the best for as little money as possible and so do we. The best are expensive and can still have problems. We are dealing with very sensitive diodes and electronics and tend to push the diodes to much higher output than manufacturers recommend. There's no perfect laser out there. All we can do here is try and point someone in the right direction for the amount of money they are willing to spend.
When you first posted your question you were.likely expecting a quick answer just like most who have done it before you but now you see what happens from what you thought was simple. Suddenly you have all this information and what was originally thought of as simple has branched out into never ending questions. I'm not getting on you at all about.it, it's just what.happens and everytime another person asks we all sigh and say here we go again in our heads. Also remember that everyone is different and have different levels of experience and some think they know the answer but are incorrect. I certainly don't have all the answers but I try and help out with what I believe to be correct.
Anyways, all that was not to be taken personally. It's just an example of how it's really necessary to spend time learning about what you are.getting into on your own by spending a LOT of hours or days searching the forum for answers. Most members will not jump in and try to help with the kind of question you asked because they are so exhausted from trying to answer it a 100 times before when it just results in never ending questions.
I tell everyone to be nicer than you have.to be and be.generous with the thanks and it will help them here. Way too many new members complain and become very impatient demanding help and that is NOT the way to go to fit in.
Again, all that wasn't personal directed at you. It was just me letting out what all new members really need to hear
Honestly all new members need to read all of that.
Pete
After all that the answer to which one to buy for visibility and burning is the 1W blue