This might help... Here are the mech mods I have bought, with some comments...
1. Smok Magneto, brass, no logo. Bought two of these as gifts for my son and his girlfriend to replace their old broken vape gear. Got it from vapingcraze.com (about 35 bucks on sale IIRC), and it is pretty decent. Tubes are not overly thick but strong enough for careful use. Threading was clean and even. Spring loaded connector in 510 connector was flimsy, and the spring broke on my son's mod... we bought a replacement head to repair it. Works fine since then, but I would not buy another one.
2. Hcigar Sentinel M16 clone, bought this for myself at Bucky's Bargain vaping... I think it was $36. Much more robust and precise construction than the Magneto. Materials appear superior. Threads smooth and tough as nails. Less voltage drop than Magneto. Two minor flaws: (a) threads are slightly visible in 18650 mode, and (b) button backed out frequently during use, a bit of dental floss on the threads fixed the problem (considered using loctite if dental floss didn't work, but the floss fix has worked flawlessly).
3. Hcigar King clone in stainless steel, about $50. Holy crap this thing is solid and heavy. Excellent fit, finish, materials. Flat spots on octo-rings keep mod from rolling on uneven tabletops. Button is smooth and easy to actuate, no crunching or wobbling. Every pin is adjustable. Flaws? None really, except it is a little heavy.
4. Fasttech Launcher V2 clone. This thing was less than $20 and it is made as well as the Hcigar clones I have. Fit, finish, materials, and design are all excellent. Solid copper pins, fully adjustable. Fully equal in performance to the King clone at a fraction of the price. No flaws that I can think of. Amazing value, and it is my favorite mech mod right now. Highly recommended.