Local secondhand markets are your best bet. Ebay has many listings, just be a smart shopper and don't fall for obvious scams or buy a broken tablet. You can look at other brands if you can't afford the prices. Seems to be many tablets around 50USD for a reasonable condition, which is honestly a good price, I bought mine for about 75$ in 2019.
If money is a big issue, try other brands like XP-Pen or Veikk. I got to 5 digit with a veikk and my friend got to 10k rank with it. You don't need a Wacom tablet to improve, but I understand if you want to buy because of the brand or quality. Another option from is the CTL-472.