A list where thrift stores were not allowed may be more applicable to all locations. Some areas have thrift stores with outdoor gear, some do not. Thrift stores are great for clothing. Particularly since the generation now dying (their heirs giving those old outdated clothes to Goodwill) had really nice wool stuff, cashmeres for a few dollars.
One item that struck me was the $10 compass. I no longer use a compass so my cost is $0. The list says nothing of maps. I suppose you could use your smart phone for maps. I would think a person who owns an smart phone, is paying nearly the $300 in a few months of service. Quit the phone service, or even drop cable TV and you can upgrade to a $500 gear list!
A couple of methods not mentioned.
Sewing. We used to do this a lot before manufactured gear became so commonly available. Of course you have to have the sewing machine. Used to be everyone had a sewing machine at home, not so nowadays. I made a pack bag from all my old nylon stuff sacks. I use it with the pack frame I bought at the REI garage sale for $20. My daughter used to live in San Francisco and showed me all the super discount fabric stores in the Chinese districts. YKK zippers for 50 cents. Huge commercial spools of thread for a couple dollars. Fabric at wholesale prices.
Shared gear. When I grew up we had some camping gear that my brother and me shared. He got it one weekend and me the other. Also if you hike in a group, several people can share the cost of a tent. Cook gear should suffice for a group of four.
Multipurpose gear. I do take issue with the concept of a cheap sleeping bag. If a beginner spends a sleepless cold night their first trip, they likely will never go again. And a sleeping bag is not a backpack-specific item. It comes in handy for all kinds of travel. I personally buy higher quality gear, but then use it both at home and backpacking. I have a $50 down jacket I got at Target that I use as my town jacket because it looks nice. I also take it on some backpack trips. I wear my fleece layers at home as well as backpacking. My dear husband likes the house temperature set at 66 - I would freeze if I did not wear my backpack fleece! Raingear, too, is multipurpose. I do not have "town" raingear - I just use my backpack stuff.