Has anyone sold over $35k worth of equipment over the net? How do you protect yourself?

I’ve used escrow.com to good effect. The fees are relatively low, and transparently declared here. For larger amounts, it's convenient for the buyer to be able to wire the money to them, and they will then wire it on to the seller after the escrow is released.

To be clear, escrow services like escrow.com exist precisely for this purpose - to protect both buyer and seller in an expensive transaction, and they charge relatively modest fees. Buyer sends money to the escrow service, the service tells seller to send the equipment to buyer, and there’s an agreed-upon inspection period. If the buyer is satisfied, the service releases funds to seller. Otherwise, buyer sends equipment back to seller (at their own expense), and once seller confirms receipt, escrow service returns funds to buyer. There’s professional dispute resolution if things really go south, and it’s certainly still very useful to vet the counterparty before the transaction - but this is mostly a solved problem.