I rather like the new board but since we're talking low-cost alternatives one thing to consider is buying Arduino-compatible boards directly from China.

My personal experience with boards roughly the size of the Trinket has been as follows: I have purchased a Pro Micro [1] compatible with an ATmega32U4 chip and an on-board MicroUSB port from a Chinese seller on eBay for under $9 as well as two no-name Arduino Pro Mini variants with ATmega328 chips from two different eBay sellers for around $4 each, all fully working. At their price point the latter can compete with ATtiny85 chips directly despite being noticeably more powerful and more convenient to use in many cases. I can't say much about the long-term reliability of those boards (my guess is that if you buy enough of them you'll notice that on average it isn't that great compared to that of boards with officially sourced MCUs) but the ones I got for myself and acquaintances (different models, six total) work as specified for now. The oldest one is over a year old and has been used in several different projects including one that ran continuously for 160+ hours.

[1] An Arduino-compatible board designed by Sparkfun, https://www.sparkfun.com/products/11098

[2] http://arduino.cc/en/Main/ArduinoBoardProMini

My experience with the launchpad has been mixed. The chips are definitely aimed at the low power, low requirements side of things; I had a project where the MSP430g2231's inability to clock from an external high-frequency crystal was a dealbreaker. There's also a wider breadth of hobbyist software targeting the AVR.

If you're a hobbyist, it's definitely not worth saving a few bucks if you're only making a few of them and you account for the value of your time. YMMV.

While it can't use an external xtal, it still has an internal crystal oscillator which can clock it at some MHz, up 16 MHz I think. It's not as accurate but cheaper and more flexible. I did a port of the Contiki OS to the Launchpad, which now comes with the msp430g2452 (16kB flash/256 B RAM) and the 'g2553 (16/512). At home I have them using cc2500-radios (2$ modules from aliexpress) and a radio duty cycling protocol I wrote, with plenty of flash space left for user applications.

You can find the port at https://github.com/msloth/contiki-launchpad and a write-up at http://www.bithappens.se/blog/2013/05/26/contiki-for-ti-msp4... and http://www.bithappens.se/blog/2013/05/26/simple-yet-efficien... with lots of measurements and other crowd pleasers.

The g2231 etc certainly are not specced to work from high frequency crystals or oscillators, but in actual use it works:

http://forum.43oh.com/topic/594-use-a-12mhz-external-square-...

I was under the impression that the newer chips are able to clock from an external crystal. My 2553 certainly came with one, though I have had no need to use it yet.

That's the crystal for the slow clock, which runs at about 32kHz. You still can't clock the main clock off it.

The launchpad works with any MSP430 that fits in the socket, including smaller chips.

This has 8 more pins than the LaunchPad and is a bit cheaper: https://analog10.com/store/BOB-G2553-28.html You can drive motors from those pins while keeping your P1 free for comm peripherals.

Looks like it's a software implementation [1].

[1] https://github.com/adafruit/Adafruit-Trinket-Gemma-Bootloade...

An ATTiny85 in DIP also runs unassisted. That's not the point of this board, though.