Don’t assume the seller isn’t willing to pay eBay fees for some small protection on their side. They’re selling an expensive bit of kit, they’re using a platform that charges, but offers to protect them as a seller and handle payment for them. With eBay Payments now, and the collection codes, it’s much harder for a fraudulent buyer to game the collect in person scenario and say something isn’t as described any more.
If you want to make an offer, send them a message with your offer and if they accept, ask them to send you the offer back using eBay’s mechanism, intuitively titled “Send Offer”. Then either pay using a credit card, or cash on collection of the agreed amount. If you want to view, then arrange a viewing before doing any of this. Whenever I’ve sold bikes on eBay, including some worth a lot more than 1700, I’ve always insisted buyers view the bike before buying anyway.
Personally, anyone asking to do a deal outside eBay gets a short shrift from me. I’m using eBay for a reason and I’m well aware of the fees. Otherwise it’d be in the Wild West of Facebook Marketplace and Gumtree.
Oh, and eBay doesn’t really use PayPal any more. I’m sure you can still pay with it, but it’s not their payment handler now.