In cases when I intend to buy something (for internet marketing) and a provider's only contact option on their website is email, I do go ahead and email them. However, at the same time, I am in contact with other (sellers) websites too. Usually, I am not an impulsive type of buyer, so I'd wait for a day or two before buying and if by then any replies have come by email, I include those sellers as well into my "bucket" and then make a buying decision. A few times, I got lucky waiting that extra time, as the email only contact type of seller's deal (pricing), quality, etc have been better.
It is worth the wait for a day or two, if incase one is not in a hurry to buy.
And just because the only contact option is email, it does not necessarily mean that such a website (seller's) service or product is not good.