No that's a pretty diluted cart. On average 1 gram of concentrate will have around 750mg thc. Do the math to make sure you're not paying too much. And there's no telling what they're cutting it with, there's some really bad stuff out there used to dissolve and dilute. I would pass personally.
You'll have to vape more than you think for desired effect at that ratio, depending on tolerance anyway. Sounds like you're eager to give it a go, see what you think of it.