Instant eBay saved search alternative that doesn’t require constant buying?

Hi everyone. I like to collect rare VHS tapes, and there are a few super obscure ones I’ve been hunting for. Because they’re so rare, it might take years before they show up again. What I’d really like is a way to get notified instantly when they do, so I have a better chance of grabbing them before anyone else. I know eBay saved searches only update once a day, which isn’t really fast enough for what I need. The problem is I don’t buy on eBay very often. I’m on a low budget, so I usually only purchase when one of these specific tapes shows up. I don’t want to lose notifications just because I’m not a regular buyer.
Are there any websites, apps, or tools that let you set up alerts for eBay items and keep those push/email notifications active indefinitely like even if it takes a long time before the item appears? Ideally something that’s reliable and doesn’t require daily manual searching.