Are Google Sites an adequate platform for a site that offers firearms training?

I built this site for a client, using google sites.

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Biggest problem is checkout. The only google gadget I had for checkout requires google wallet. My client is so frustrated with google wallet, that he no longer accepts online payments, and requires his students to bring a check to his classes.

I feel this is a huge failure on my part. I suggested using google sites (price was right, and traffic is very modest).

I am not certain, but I think there is now a gadget for using paypal.

Any advice appreciated.