Where should I start with Technic?

[GeneralNumberOne]

I'm specifically interested in power functions type things and potential integration with system, although I'm down for Technic only sets. I'm on a fairly limited budget, though ($100 or less).

[schraubedrin]

If you're focused on power functions, i'd suggest to search a used 42030. It has the complete collection of power function parts and can be available bellow 100€ (depending on your country).
New sets with power functions below 100€ are rare: https://rebrickable.com/parts/16511/electric-power-functions-battery-box-4-x-11-x-7-with-orange-switch-and-dark-bluish-gray-covers-new-version/71/?sort_sets_by=2&sort_sets_dir=D

Edited February 10, 2020 by schraubedrin

[WvG_853]

Buy used ... For new models wait until Christmas promotions or end of life stock cleaning actions. You can also put aside money to buy a bigger set. Good luck and enjoy!