with servos you truly get what you pay for. Any hobby is going to be expensive so if you want to start out small due to a tight budget, a Brat is your best bet. If that’s still to expensive, a boe bot is another good one to start out on.
Its best to keep it simple anyway because a 20 servo biped for a beginner is almost garunteed to cause frustration and eating mac-n-cheese for a few weeks/months/yeas to recover from the expense.
even cheaper - getting the “what’s a microcontroller” book that comes with the mcu and parts for experiemts. With this book you learn about simple circuits that control the mcu in some way. Its a great starting point and gives you the basics.
Bad linearity, low quality MG gear and poor accuracy. Some of them also has an annoying hysteresis when reaching its position.
