I have also bought various building materials on Craigslist. Most recently a 32” Fiberglass exterior door for $100. Many times people will order a door and buy the wrong size, swing, etc. You can not return a special order.
This door would be about $300 new.
I have bought hardwood flooring, furniture, tools, snow blowers all on Craigslist. I am currently looking for a used Kubota 29-30 HP, L series compact tractor. Brand new they are $30K. Used $12-19K depending on the hours.
I will never buy anything new again. Just keep checking and wait for what you want to come along at the price you want to pay.