They can be, but a tablet is an important tool worth investing in.
Not all tablets are $300 lol. There are lots of different types! Look for low cost options.
Smaller tablets cost less, are more portable, and can be easier to learn with.
Refurbished tablets are cheaper and usually work just as well as new units. Used tablets depend on the seller obviously.
Nowadays there are lesser known brands with cheaper units too, some as low as $40-50 for larger ones.
In general though, don’t skimp on your tablet. Good ones are expensive BUT if you take care of them you’ll get several years out of them. The little 4×5 refurbished Graphire I bought off amazon almost 10yrs ago still works great! And I’ve used my Wacom Intuos4 for 4+ years without major issue.
Do your research! Shop around, check reviews, see what other artists use and recommend.
If you’re pursuing digital art, a good tablet is 100% worth the investment YOU WILL NOT REGRET THIS DECISION.