I think the reg set you linked to will serve you well. I find Mares regulators to work just as well as just about any other brand on the market. I dont expect you would have issues with it should you purchase it.
That being said, I cant comment on whether the price is a good deal or not, as there are various factors that factor in to that, some being personal in nature. I will state, however, that if you dont plan on servicing the regulator yourself that you should strongly consider the hassle to find a service center and the expense of service in the equation of whether or not you consider the sale price as a "good deal".
Also, realize that by purchasing from a website, if there are any adjustments that need to be made to the 1st or 2nd stages, you will need to find someone to provide that service. It is not incommon across all brands that a regulator needs fine tuning between unboxing and first use. Usually a shop will check and tune the ref if necessary before it walks out the door. It is debatable whether the website you are purchasing from does this.
-Z