But now when they hear that the price is ~$150+ their response is, "Oh it's too high. It's risen too fast, too quickly." If however, the price was $1.50 or even $15+ they would probably jump in and spend just as much money. It's a psychological thing, like buying a thousand penny stocks vs spending $600 on a single share of Google. ...
I think the key is how you describe it from the beginning. Try this:
"A bitcoin is like a one ounce gold coin, although it actually works better. There aren't that many bitcoins. There are 500 ounces of gold in the world for every bitcoin. An ounce of gold is currently valued at about $1600. A bitcoin is less than $200. The millibitcoin, which is one thousandth of a bitcoin, is more akin to the U.S. dollar and currently costs 19 cents."
Of course, you'll want to balance that with a realistic discussion of the risks.