Continue with doing smaller trades or do what "Rodeo02" mentioned
[on an exchange]...
What should I do or suggest to the seller? An escrow of some kind? Thanks for your help.
By doing that, the escrow provider can only protect your part of the deal
[since you're the one with reversible method] and not the other involved party
[seller] which means, it defeats the purpose of having a middle man for protection.
PayPal - regular Most world currencies 0 Extremely easy to charge back. Also, since trading bitcoin is against their ToS, good luck disputing the chargeback. Do not use.
This will always be in the discretion of the seller, since they have been doing a Paypal for Bitcoin exchange without escrow for several times now I highly doubt that he/she would even deny the OP if he requested an escrow for their next transaction especially if it would be a substantial amount as said by the OP after all the seller is the one who is accepting Paypal payments for his/her Bitcoin in the first place. @OP if you are still having doubts with the person even though he is a trusted member you can never go wrong by availing an escrow service since it's your money we are talking about you will always have the right to protect it from any potential scams.