Purchase Agreement: Standard or Custom?

[Frederick McCarty]

Hello. When contracting a seller is it better to use state specific purchase agreement or a custom one? I want to use the Purchase Agreement template from Indiana Association of Realtors, but it appears they want to discourage it's use by non-members. I have a few different examples and wondered if a hybrid of them would be better? I've heard of issues with seller's being leery of signing documents/contracts that didn't appear original. I have no problem doing my own, but wanted to inquire before I waste time.