Marketing my niche product is harder than I thought – I need help!

Hi everyone, I’m a solo founder working on a niche project in the Tesla space. My platform connects buyers and sellers of used Teslas in France. The idea is simple: sellers pay to post their ad on my site, and buyers can sign up for free to receive curated listings via a newsletter. I thought it was a straightforward concept, but marketing has turned out to be way more challenging than I expected. Here’s what I’ve tried so far: 1. Google Ads: I targeted “Tesla for sale” keywords, but the cost-per-click is high, and conversions are low. 2. Facebook Groups: Many Tesla-focused groups don’t allow promotional posts, so I can’t directly promote my platform. 3. SEO: I’ve started writing blog posts to drive organic traffic, but I know this will take months before it makes an impact. So far, I’ve gotten around 60 newsletter signups, which is a start, but I’m struggling to scale beyond that. Here’s where I could use your advice: • How do you attract sellers (or buyers) without relying heavily on paid ads? • Are there creative ways to tap into niche communities (like Tesla owners) without breaking rules or spamming? • Have you had success with marketing a paid product in a super-specific niche? If you’ve navigated similar challenges or have creative growth tips, I’d love to hear them! Thanks so much for your insights 😊