If that's what you can afford, then it's better than using just tap water or paying for 1/4 of the unit's cost just to do that big water change with water bought from the LFS.
If you can hold off until you can spend $150 - $175, there's a lot more options out there from a variety of reputable and respected online retailers. I only say that because I've read many posts by people that bought cheaper units and struggle with them due to the relatively poor tap water quality they have. They end up spending more money to upgrade their cheaper unit only to have the total cost with upgrades exceed the cost of buying a better unit from the start. However, if you have really good tap water, it's likely that a cheaper RO/DI unit will do all that you need it to.