Honestly, the extension situation for watch tracking is pretty abysmal. I had high hopes for a few of those browser tools but they always end up being a total headache... not as good as expected at all. For a $5k purchase, you really want reliable data. Since you're on a deadline for your brothers gift, forget the buggy scripts and try these instead:

• Go to PriceDropCatch to see if you can snag a better history on that specific reference without the browser crashing.
• Manually track the 'sold' listings on eBay to see what people actually pay, not just the asking prices on Chrono.
• Use Chrono24s own Watch Collection tool by adding a dummy watch; it gives you a rough market graph that's actually decent. Tbh $5200 for a 2018 Moonwatch is okay, but if the seller is playing games with the price, they're probably just testing the waters. Don't let the clock stress you out too much, you've got this.

Unfortunately, those extensions were a total letdown and just crashed my browser. I gave up and used the Chrono24 valuation tool instead to track my own 2018 Speedy.

I tried messing with those GitHub scripts last year for a Seamaster and honestly, it was a total mess. Not as good as expected and it felt super risky for my browser security. Unfortunately, most extensions for this are buggy as hell.

• I started using PriceDropCatch instead to track those price swings.
• Its way safer than installing random scripts.
• It actually catches those annoying price bumps you mentioned.