Imagine you’re shopping for a new home in Butler and you find a great house for $150,000. You ask a local bank for a 13-year mortgage and offer to put down 20 percent, plus closing costs.

“Congratulations,” the banker says. “We agree to lend you a $140,000 mortgage.”

Then the banker leans across the desk and says “I have a great offer! For the rest of the year, you will have a principle payment of zero! Just pay the interest.”

But wait. There’s more.

“It gets better,” he says. “For the second, third, fourth, fifth, sixth and seventh year of the mortgage, you will have a principle payment of just $50 per year, plus interest on the outstanding balance.”

It won’t be until years 11, 12, and 13 that the principle payments will increase to $46,400, $54,800 and $25,400 per year, respectively.

That’s a great offer — right up until the money comes due in year 11. From then on, it stinks.

Who would take that kind of offer?

Well, add a few zeros, and that’s essentially the PNC bond financing deal that the Butler County commissioners approved last week to pay for the new $15 million 911 emergency system.

Commissioners Kim Geyer, Kevin Boozel and Chairman Leslie Osche said they’re following the advice of their financial consultant, PFM Financial Advisors of Harrisburg. County Controller Ben Holland criticized their decision, saying it benefits PFM more than it does the county or its residents.

Who is right? Your guess is as good as ours. But this much is certain: Somebody must be wrong.

And the commissioners apparently made up their minds before hearing Holland’s objections.

Here’s the deal, as reported last week: Butler County will repay $14 million over 12 years under the PNC bond financing. The loan’s interest rate will range from 2 percent to 5 percent, depending on the year.

Starting in July, the county will pay interest due; the payments slowly descend from $276,125 to $249,500 through 2027.

Beginning in 2018, the principle will be repaid at $5,000 a year through 2023; then $30,000 in 2024, $635,000 in 2025 and $655,000 in 2026. The bulk is to be repaid the last three years: $4.6 million in 2027, $5.8 million in 2028 and $2.5 million in 2029.

Geyer called it a “wrap-around” structure, with those final three payments correspond with the county’s previous debt being repaid in 2027. That would make sense — if the county doesn’t encounter a single capital project or emergency for the next 12 years.

It seems risky not to pay down more of the principle on a loan for electronic equipment that might or might not still be serviceable at the end of the 12-year loan period.

Holland doesn’t imply that any laws or ethics rules were violated, but there certainly was an air of esoteric ritual in the way this deal was done, without bidding, without an airing of dissent, and the total of PFM’s compensation obscured by the process.

There’s credence in Holland’s claim that PFM almost guarantees a refinancing of the bond down the road. The massed principle of the bond arrangement does sweeten this honeypot for future plunder.

When boiled down to its rudiments, there should be no difference between buying a 911 radio system and buying the money that’s needed to finance the purchase. Seek competitive bids.