There are as many "Grail Watches" as there are people who pursue them. Each has their own. It's not the watch that makes it the Grail piece, but rather what the watch DOES to the wearer. Hopefully, it's something directed inward and positive.
Whatever you find for $400 will require servicing, and for a chronograph, service will run between $600-800 to get it running according to engineering spec (assuming no additional parts are needed or parts are attainable). I recommend increasing your budget to $1500, then shopping on Vintagewatchservices.eu. Stian offers numerous YouTube videos of his restoration work, which includes chronographs, so you can see for yourself the skill involved in servicing one. If you buy one of his watches, you can rest assured it was done properly and is legit through and through.
The search for the Grail is not about seeking something outside you, but the search deeper within for one's True Self. A Grail watch adds to one's sense of wholeness. How this is done is up to the wearer.
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