A no-alterations-needed silk vintage dress, bought online, for a few hundred dollars!

 No, it was not pure luck. As with venues, the game here is partially finding the gap in the market, and partially just search time. You make a good deal when you want something, and would in theory pay more for it, that others don't want and wouldn't pay more for. Potential gaps to exploit: buying a secondhand dress period; buying a specific kind of vintage dress; having a niche size; using eBay or ThredUp or whatever versus Etsy or Stillwhite; buying a dress that just happens to be white rather than a "bridal" dress, etc.........

Here is how you can have the same experience:

1. Received wisdom is you have to try everything on because what you like may surprise you. This probably is good advice, but I did not follow it. Instead, I:

    a) Spent some time looking at not just bridal fashions, but evening gown fashions overall. Thinking about what I liked, and whether I still liked it when color was stripped from the equation (I wanted a white dress, though not everyone does!). I thought I wanted a strapless dress with lace, but nothing in that category inspired me, likely because I...

    b) Reflected on the pieces I already have and love. Bridal fashion is largely a difference of proportion, not concept. You probably already gravitate towards silhouettes that you feel comfortable in.

    c) Learned keywords for better searches. You do this by following 1(a) and 3 and reading the descriptions for options you like. I started out looking for bias-cut vintage gowns, but rapidly realized that my favorites were better described as 1930s-era, candlelight-colored, slipper satin/Jean Harlow gowns. That helped me refine my searches and learn the market. 

2. Know your measurements. There are lots of guides available online. If uncertain when reading a dress's measurement online, it's safe to give 2-4 inches of "ease." 

3. Know your sources. In addition to eBay, Etsy, and Stillwhite, I frequented Ruby Lane and Fashion Conservatory, and would regularly enter my keywords into Google Shopping to see what other sources were out there. Try high-end consignment or thrift that people wouldn't think of for bridal -- I found some elegant evening gowns for great prices on TheRealReal. Not entirely proud to admit I spent 1-2 hours every day for at least a month or so getting a sense of inventory and styles, but simultaneously, this is a big expense and should be approached accordingly! Take time to know the market. I learned that, ESPECIALLY when it comes to vintage, the exact same dress in the same condition can go for $200 on eBay and $2,000 on Etsy. If there are physical locations near you, of course you should explore these too, but there is way more luck involved in this because the selection is naturally smaller.

4.  Of course you need to know your budget. Part of that is also knowing what you want to do with the dress after the wedding. If you won't be sentimental and go into this planning to sell the dress (realizing you won't recover anywhere near the full expenditure), that can offset some of the cost, but shouldn't be treated as a certainty. 

This all sounds so practical. Now let me show you the magic it awakened. This dress was secured for about $400 on eBay. My sister showed me how to use a bidding app where I could set the absolute maximum I was willing to pay, and it would outbid others up to that amount. It was handmade in the 1930s by an unknown designer out of pure silk. It needed no alterations save for taking in the belt. It has no tag, consistent with its vintage, and the eBay seller could not tell me anything.  I scroll sewing patterns and read Fashion Conservatory, and sometimes see designs that look like they could be related.

Some hundred years ago, someone with my exact dimensions wore this dress on a day that changed her life. Did she sew it herself? How did she find the fabric? What happened to the dress during the depression and how many times has it changed hands or graced an altar? Tradition and continuity of generations were central features of our wedding. I feel so thankful to have found this dress and become a part of this treasure's legacy, and it a part of mine.