No, I do not agree all the samples policy above, it is too simple.
You should set the policy on different step:
1 New customer (What kind of sample policy)
2: Old customer (What kind of sample policy)
3: If they paid the money for sample, what kind of condition you will return them.
4: Once what kind of degree of business you have dealed then you will offer the regular samples for development in free charges.
5: First time, how many times you will send the samples with charges, but how many times have no order then you will reject send to again.
All the points you should consider about it, then list a rules, send to the customer.
I think this is fair and reasonable system, the customer will understand it.
Now many customer will be interested in the first time they will pay the charges for samples, but after the order you should return, of course it is base on the amount or quantity of the order. then you send the regular samples for their development.
If they feel the cooperation with you is smoothly, they will prefer the business with you only, no need change, because they change a new supplier, they will have to face many question against the changing.
Anyway, the quality is best important, the quality is good, and let the customer win the money, the samples charges is little case to them
.
Base on this princple: Your customer can be strong, then you will. If you have the real problem, do not worry to tell them, if they really do not wanna do with you, also do not be disheartened, because it is not due to your quality of products.