How much do you pay for NGC Registry Points?

I am relatively new to registry sets, but I think it is fun. I collect mostly jefferson nickels because that is what I can afford. I wanted to share the criteria I use to determine if a coin is a good deal with regard to adding it to my registry set. The rule of thumb I use is spend no more than $1.00/registry point.

For example, almost every late Jefferson proof is either worth 3 registry points (for all grades through PR69UC) or 102 points for PR70 UC. There are a few exceptions like the 2006-S which is 183 points for PR70 UC, but most are in the 100-200 point range for PR70 UC.

Recently, I was lucky enough to get two 2006-S PR70 UC 2006-S Return to Monticello nickels for $50 for both on eBay. That equates to just under $0.14/point ($25/183 points). On the other extreme, tonight I saw a 2005-S Bison PR70 UC nickel advertised at $360, or $3.50+/point. So one was way under my rule of thumb and was a no brainer Buy It Now. The other sings "Just Walk Away..."

What are your thoughts/experiences on $/points?