It's a good point but the sub-$3 range is for the China variety of the clone. These clones often have varying pinouts, especially around the Vcc/Gnd area of the board. So caution needs to be utilized and the realization that one board ordered today may differ from one board ordered two months ago.
Plus the FTDI connector is completely randomly oriented on them. You have to look where Vcc is every single time you connect one.
The other issue, which should be considered, is the need to have a soldering iron and decent skills in using said iron. Even if you just need to solder the headers for breadboard use. Soldering and unsoldering wires to the little boards will eventually cause copper foil lift at which time the board.
Yep. The first thing you need to do when you open one is get out the soldering iron. Not exactly beginner-friendly.
It is a cheap and viable solution, but not one that I would recommend for the "My First Arduino" award.
Agree. Develop with the Uno, save the Pro Minis for building into the final gadgets.
My last shipment of 5 Pro Micros and 2 dead units... one was revived with reflashing the bootloader for the 32U4 but one is eternally dead. The previous 10 Pro Micros were 100%. 2 duds out of 15 may be an unacceptable rate of failure and most newbies will be unable to flash the 32U4: something to think about.
I've gone through 30-40 of them and haven't had a problem yet (touch wood). Even so, I don't see that as a big deal. What's a few dead ones when they're $3 each with free shipping? Just make sure you always order plenty of spares so you're never in a hole waiting for slow shipments to arrive.
I usually buy the ones with ISP connector and flash them with optiboot as soon as I get them so the bootloader gets overwritten anyway.