Mars and so many of the others DO work but are limited by the fact that they overstate their specifications (lie) and the color of the light is way off. Heck, you can grow some cannabis with almost any light source but the outcome will be limited by the performance of a given light.
In other words, my beef with Mars and others like them is the falsification of what the lights are vs. their actual performance. People raise cannabis crops under them all the time but the results would be better with a quality LED system.
If your really into growing and are going to stay with it then I would encourage you to struggle to do it with the best quality you can afford. I have been growing just 3 years but I am quite committed to it and if I had done some things differently I would have spent a lot less over that period of time. It is quite easy to waste a lot of money figuring it all out. However, I don't worry too much about it because some of it was a natural process of bumping around hitting my head and making mistakes (learning).
Dee