No. If Bootstrap were conveyed under GPL, or another copyleft free licence, and if templates were (in copyright terms) derivative works of Bootstrap, then the templates would be required to be conveyed under GPL also, and could be distributed as you have described (though the buyers in your example would have to resell them with GPL rights attached, which might not be a great business model).
But the MIT licence, like the other weak free licences, does not require that derivatives are distributed under the same terms. It is perfectly lawful to mix proprietary and MIT-licensed software, and the proprietary software does not become implicitly freely-licensed by this.
You will have to examine each of these Bootstrap templates for the terms that govern the purchase, and if (as is likely) they are non-free, you have no more right to sell copies of them than you do with, say, Microsoft Office.