I have a theory that everything has “a price”.
Let’s say you find a mint De Rosa, your size, and it’s $1,000. You’ve always wanted one but can’t stomach paying the $1k. Later you find a scabby version of the same bike for $150. Yay! What a score! Upon closer inspection the forks are bent, there’s a dent in the wrong place on the seat tube, it’s sporting a Huffy saddle, the brakes are mismatched low-end Dia-Compes, the wheels are 27” (you wanted 700c) and the paint is awful. You’ll spend a fortune righting the wrongs and equal or exceed the $1,000 version.
My point, if I have one, stuff costs money. Horse trading to get the correct bits is fun if you have the time but it takes patience and knowledge. Personally, I would rather rely upon knowledgeable people like the fine folks here and get the correct stuff the first time. The thread about buying a bike for a seat post isn’t my thing since after they get their seatpost I might chime in and ask about some of the other bits on the frame I could use.
I’ll step off the soapbox…