Is the seller in the US? If not, I'd have very little doubt that it's a scam. If they are, well... I'd still avoid it because it always feels sketchy when someone is trying to push me off the site.
PayPal, with all its claims of buyer protection, can be difficult to deal with once you've been victim to fraud on Reverb.
As an aside, Reverb is overrun with scammers and my experiences in the past year are a testament to that. I made the mistake of jumping on a too-good-to-be-true deal on a Fender Jazz Elite (coming from Australia)... after some kind TB'ers talked some sense to me, I attempted to cancel the order within just a couple hours. Notified both Reverb and PayPal of my suspicions for fraud the same day, and both were content to let the whole thing play out.
Seller then sent a 2 lb package to a different address in my zipcode and provided tracking that made it look like it was delivered, though without a specific address listed on UPS tracking. Seller sends PayPal a scan of a label that looks like it was addressed to me. Even though this was the exact scam I predicted to Reverb and PayPal customer service, I got nowhere. PayPal sides with the seller since their fraud bot believes shipping was confirmed. Reverb does nothing but tell me they'll be happy to work with PayPal if I have any issues (though there's really no way to make the 2 talk to each other).
Nobody seems to care that an electric bass sold from Australia ends up being a 2 lb package sent from Germany. Tried appealing but wasn't getting anywhere. PayPal then bowed out completely when I took the dispute over to AmEx. AmEx initially made the same default decision to side with the seller based on tracking, until I was able to show them that UPS confirmed by email that the recipient address on the package did not match my address. The whole thing took about 2 months and a lot of wasted time to get my money back.
I can say with certainty that this particular scam is common on there, as I have seen 2 of my own personal bass listings (originating from my Craigslist ads) get re-posted to Reverb with partially copied/pasted descriptions, coming from foreign countries, at below market price. I have also gotten numerous bogus messages from buyers on my actual Reverb listings, asking me to email them to discuss a sale. To me, the platform seems pretty unsafe at baseline. So I'm easily sketched out by what was described in the OP.