For me, the items that make most the difference between being comfortable and miserable are shoes, sleeping system (bag and pad), and backpack. All are require an individual fit.
Shoes are the hardest for me. I honestly think just wearing over-sized comfortable running shoes with Smartwool socks is the best way to go if you stay on trails. Most people really do not need boots.
A sleeping bag is like a pack - you have to get inside it and see how it feels and fits. I would not go cheap on the sleeping bag - it has so many other uses - not just backpacking - car camping. I even have unzipped my down bag and used as an extra comforter on my bed at home. There are good medium priced down bags - in the $250-300 range on sale. Personally I would not buy a used bag. The yuk factor is just too much for me. (I also will not sleep in my husbands bag for the same reason). You can wash a bag, but never truly sterilize it.
A moderately comfortable pack is OK with me. I have gone years with a pack that theoretically does not fit me. If you are packing weights in the 25 pound range, less than perfect is OK. If on the other hand, you are doing 40-50 pounds, a better fit and pack is needed. Almost all my packs cost about $150 or less. (my sleeping bag cost $500) There are TONS of sales on packs. Thing NOT to care about in a pack - color. Do not assume that all women need a woman's specific pack. Depends on your body build. Try both women's and men's. Women's packs are built for narrower shoulders. If under 5'4" women's packs probably will fit better. In fact, if short you may want to try a kids pack. But if you are a bit taller and wider, a man's pack may fit better. I am currently using a Golite Quest. I do not think they make that one any more.