I am a big fan of CKS. So far I have had 4 deliveries from them without issue. I have tried others and had issues. CKS is easy to work with and they have a very good selection.
Not sure why,but my order was rejected saying Bank does not accept charges from outside areas? Never had problem before ordering things from other countries?
You may want to call customer service. I had no problem using a card at CKS but was not able to use it at two other places I tried. They may suggest that you call your credit card company and see if you can allow the charge.
It is safe to send cash. I sent cash to a supplier in the UK and had my seeds back exactly 2weeks after I mailed the cash. With CKS it's very easy to just use the chat on their site.
The Single Seed Centre is another fantastic seed bank. Instead of ordering a pack of one strain you can order a bunch of single seeds from multiple strains.
I consider the hardest part of growing marijuana to be choosing the right strain to grow. No all strains are created equal. Even seeds from the same plant can vary significantly in terms of potency and characteristics. Its very important that you choose a strain with an iron genetic backbone. For example, Jack Herer is a strong, stable plant that will consistently produce potent bud, time and time again.
But thats what I love about ordering from the Single Seed Center. You can try many different strains all at once. Growing multiple strains is the only way us regular growers can measure a plants potency by comparing against another plants smoke.