I bought one of these to mess with: https://www.amazon.com/dp/B00SK8LNYG
Currently $9.84 (free S&H) for a breakout board. 100kHz to almost 300MHz, controllable over I2C. Two independent clocks (choose frequency, turn off and on, and possibly relative delay (never tried delays) plus one dependent one. Works great on the Arduino, possibly a little finicky on the ESP32 (might be me). The chip itself is something like $1-2.