There is no way around: we have to buy a few things before we hit the trails. But - we don't need to have multiple pieces of each kind of gear. It's enough to get one, but a good one.
Don't get into the faulty of buying cheap gear, as it can be a quite short-sighted decision. As I know very well what it means to travel on a budget, I understand the struggle.
There are things we can save on, and items we should get the best quality we can afford.
As my father used to say, "We are too poor to buy cheap", and I try to live by that. Pick and choose where I can save and where "saving" would backfire to cost actually more.
How do I stay on a budget? I save on clothing. But not on their quality - I have very few items, but they are of a good quality. I also got some second-hand, as high-end products tend to last long. I signed for multiple newsletters from outdoors stores waiting for sales and promotions.
I also save by camping instead of staying in hotels or B&Bs whenever it's possible. I don't eat out and save all year on a variety of pleasures to have money for what I think is of higher priority.
In addition, I buy the big price items in stages. Last season I had to buy a lot of things, so I splurged on the most important items: boots and a backpack and the rest got second-hand, budget versions, and the bare minimum in number. This season I upgraded a few things: I got an absolutely amazing down sleeping bag. Next, I hope to buy an ultra-light sleeping mat and another backpack - this time smaller and lighter. In the future, I might get a lighter and sturdier tent.
EDIT: I am happy to say that I updated my sleeping mat to an ultralight Therm-A-Rest NeoAir (I love it! A full review soon) and exchanged my budget (but good) Vango tent to an ultralight Double Rainbow by TarpTent. I hiked another season with Deuter AirContact and still love it - I had a very heavy load at times but my back was in good hands (or back support).
EDIT 2: I just got Therm-a-Rest NeoAir Xlite sleeping mat - you can read my review here!
Below I gathered basic items from hiking clothing, gear, food and other needed items.
Are those the only worth buying? Of course not, as a lot of that is subjective. Buying from a well-respected company (like the North Face, Arc'teryx, Rab, Solomon, Icebreaker, MSR, Patagonia, ....etc.) generally means high-quality product.
I read a lot of online reviews, as I am anxious about spending a lot on a thing I wouldn't love all that much. Especially, that I mostly buy online with no way to try the thing on. Thank goodness for free returns! :D I tried and/or bought & sent back at least a dozen pairs of hiking boots before finding the pair I loved!