If you are doing a bullet journal, there are many options but we highly recommend you buying dotted journals as it will make it easier when you are planning spreads. You can get those for cheap at amazon, walmart, or michaels. Although, you may have to look a little to find a good cheap one. Some on amazon we personally recommend for cheap prices are...
https://www.amazon.com/Clever-Fox-Dotted-Journal-2-0/dp/B07V8KHPX4/ref=sr_1_17?dchild=1&keywords=dotted+journal+a4&qid=1610392843&s=office-products&sr=1-17 You can also get graph journal ones if you prefer those...
https://www.amazon.com/gp/product/B075QMHT3M/ref=ox_sc_saved_title_3?smid=A16MMQBSKNGESZ&psc=1 ^^usually recommend these to people doing other types journals that are not bullet journals, but any of them would work no matter what type you want to start There are probably many more journals that are cheaper, but these are personally the ones we recommend. You can also find more expensive ones that are $20 dollars and above, if you are okay with spending that amount of money. But, if you're a beginner I recommend getting a cheap one first. If you do not want to buy (dotted grid journals) from amazon but from store, walmart and michaels tend to have them as well.
Some expensive options...
very helpful!