Okay, I'll bite...once....and give the IP another free bump.....explain how a PM is "too risky". If the seller does consider your "offer" how exactly are you going to organize price, shipping address, etc, etc?
I’d be interested in quite a few at 80% of retail price. If you have any interest, let me know. I’m in no hurry.
Well, you're in luck! Many of his sets are 80% OF retail! Ex: #10235 is listed at $100.00. Bricklink average six-month sold price (not for-sale price) is $134.83. 80% OF that is $107.86. On that set, his price is already 74% OF $134.83. If what you really meant was that you wanted 80% OFF retail, you're being unreasonable and I would find the "offer" insulting.
Also, good posting etiquette would tell you that Private Message (PM) would be the best way to communicate such an offer.