An interesting article within the Washington Post outlines some of the challenges with unbound delegates and delegates available for purchase…
(Washington Post) West Virginia looks perfect for Donald Trump: a struggling working-class state filled with the types of voters who have backed him elsewhere and could deliver one of his biggest victories.
But a sweep there might not matter. That’s because as many as 34 delegates — the entire contingent — may be free to back whomever they want at the Republican National Convention.

Much the same is true in Pennsylvania, home to a hotly contested April 26 primary, where there are 54 uncommitted delegates. Other states and territories, from Colorado to Wyoming to Guam, will also send squads of unbound representatives.
These are the swing voters of the GOP nominating contest, nearly 200 activists and elected leaders beholden to nothing except their personal judgment and empowered to make or break candidacies.
If Trump arrives at the July convention in Cleveland just shy of the 1,237 delegates required to secure the nomination outright, these unbound delegates could decide to push him over the top — or force a contested convention with successive rounds of balloting.
[…] The arcane rules governing the nominating process mean that in Pennsylvania, a populous state that all three remaining candidates are targeting, the winner will automatically receive only 17 of the state’s 71 total delegates. The other 54 delegates, who are elected on the primary ballot in congressional districts, will be unbound.
“Even if you stood up and said, ‘I’m for Governor John Kasich’ and your district duly elected you based on your word, you can go to the convention and say, ‘Nope, I changed my mind,’ ” Brookover said.
Phil English, a past delegate from Pennsylvania and a former congressman, is among the 162 Republicans running to become delegates. He said he considers himself “a free agent” and is open to nominating someone not currently campaigning, such as House Speaker Paul D. Ryan (R-Wis.).
“I intend to listen to people in my community, look at how they vote in the beauty contest, and then make my own assessment of what would be the strongest ticket for the Republican Party,” English said. (read more)

Here’s a spreadsheet of Pennsylvania’s Delegates – SEE HERE –