In this case, “Value” means the benefit you receive vs. the price you pay. The simplest form of this equation says, pay the lowest price you can find, and this will increase the value to you. However, the formula isn’t that simple. You need to factor in quality and support too.
Regarding the electronics to drive your Hobby CNC stepper motors, there are LOTS of cheap (and I mean that in the least-nice-way possible) Chinese controller boards from Alibaba. Figure 1 is just one of many for around $10 for one axis.
Right off the bat – something smells wrong. How can they do it so cheap? Well, here’s the answer: Use the cheapest-crap parts you can find from any bin you can. Parts that don’t meet spec, electrolytics that dry-out and fail, questionable assembly quality. Every quality corner that can be cut, is cut.
Proof Point: in Figure 1, everything is covered by a heatsink, but you can clearly see one electrolytic capacitor (enlarged in Figure 2).
Chengx. Ever heard of them? Me neither. Google “Chengx capacitor quality”. Not good news.
Here’s a great video ‘teardown’ of some knock-off Chinese crap electronics by Dave Jones of the EEVBlog. jaycar-dmx-rgb-led-lights-teardown/. You will see an excellent example of just how many corners can be cut, how much cost can be carved-out.
So, quality is highly questionable, “I’ll just buy 5 of them to have a spare-or-two – that’s still only $50!”
Besides low/no quality parts, dicey assembly practices and no/low quality service, consider who you are going to call if there are any problems? Nobody, that’s who. You can post on a forum and hope someone else has already figured out the problem. Your time ain’t free.
You will also need a breakout board (BOB). And a 5V power supply.
So where are we:
5 boards @ $10 each ($50) + BOB @ $10 + 5V power supply @$5. So you can have the lowest quality, cheapest, most unreliable, unsupported, poorly documented solution for $65.
HobbyCNC PRO 3 axis is $76. All quality parts, no knock-offs, no grey market, no ‘generic’ parts. No BOB required and no extra +5V supply – giving you simplified wiring as a bonus.
Think about it.
CapXcon capacitors (another ultra-cheap Chinese capacitor) EEVblog #347 – Bad Cap LCD Monitor Repair
Toms Hardware, PSUs 101: A Detailed Look Into Power Supplies, Capacitors Manufacturer Tier List (Note: I only use Panasonic or Suncon)