In general, gear prices increase as gear volume (size) and weight decreases.
The volume and weight of your gear will determine the size of your pack; thus the reason I recommend that you do your research first, acquire the bulk of your gear second, and save your pack purchase for last.
My first pack was much too small for my gear. So what do you think I did to accommodate? Yep, just like most folks I attached stuff to the outside. What happens then? The pack becomes unwieldy with the center of gravity out of balance and repacking becoming a nightmare.
While buying the right gear the first time can be daunting especially for those on a tight budget, it doesn’t need to be stifling. The reality is it probably won’t be your final purchase. Consider it your starter gear. I can almost guarantee that you will make changes once you figure out through trial and error what really works for you. Remember there is no magic answer, everyone has preferences and what I call “choose your pain” points (those items you can’t live without). There is lots of gently used gear on the market, so once you’ve done your research, you can start shopping for bargains. I’ll be providing some links to help in that regard.