Last time I used a "I got the cash with me right now" tactic, I was a little pissed off when the salesman replied,

"How else are you gonna pay? *snigger*"

Obviously I walked out of there, even though I did have the cash on me there and then, $30000 in neatly stacked bills in a manila envelope.

Should have kept my composure and showed him some of the cash and then go, "See, here's your commission. I'm putting it back into the envelope and taking it elsewhere."