members creditability

This whole thing is pretty simple, If a member want's to buy something from you and want's you to hold the part or stretch out payments and you don't want to do that, don't feel comfortable, or what ever, that's your choice. You own the part and you can sell it to whoever and for whatever terms you and the buyer agree to.
Don't sell to the member under those conditions then If you don't want to.

Now, if the buyer turns into a dick and starts calling members names and such because he didn't want to sell under those conditions, then we have a problem so think twice before you comment to another member because he doesn't agree with your terms. The ball is in his court. He doesn't have to sell to you regardless of the reason.