In English, unlike many other languages, two negatives make a positive. So, there isn't no X means there actually is some X available.
However, in some dialects, notably US slang, double negations are used. These are usually in the form of there ain't no rather than there isn't no. For example
There ain't no cure for love
Strictly speaking, that means that there is, in fact, a cure for love. However, the sentence will be understood by most native speakers to mean that there is no cure for love.
As a general rule, double negatives should be avoided unless you are acting in a gangster movie or are using them for poetic effect.
As a side note, English is perhaps the only language with a commonly used double positive that becomes a negative:
Bart: I'm smarter than you!
Lisa: Yeah, right.