votrechien - 10:36 am on Apr 26, 2013 (gmt 0)
I don't know if that's enough to give you a presence and therefore nexus in Delaware. I would just call the department of revenue for Delaware and they Might be able to tell you for free (or any accountant specializing in this sort of thing could as well for a fee of course).
It shouldn't be that big of a deal regardless...Delaware customers are likely to be a very small fraction of your customers. And if you're really concerned, go base yourself in a state without sales tax.