A few years ago we needed a new front screen door for our 100 year old house. The big box store prices seemed high, but as they included installation and we were busy, we decided to have them do it. However, it turned out they only had standard sizes for the "reasonable" price, so it would have cost much more still. No way.
I went to the Habitat ReStore, found an appropriate one of solid wood (probably SYP) that I trimmed to fit with a circular saw and guide, repainted, and it's done well since then. It was tagged at $25, but when I got to the register, they told me it was half off. I did it myself, but it cost 5% as much.
For older houses the Habitat ReStore is a much better source of items that match old houses than the big box stores around here (SE WI). And if you have good stuff you don't need, it's a place you can donate with a decent chance it'll get used.