LOL, I work for an integrator that is a partner for Red Lion, Matrikon and HMS... I feel torn
As I see it, the Red Lion Data Station is a good hardware solution if you have no idea what you are getting into until you get there. HMS Anybus is better if you can plan more in advance, and Matikon is a good OPC resource if it can work for you (I like them better than KEPWare). I might add, using another HMI to connect to your SCADA system, assuming it has already been selected before you, is a bit of overkill. As was previously mentioned, the vast majority of good SCADA systems out there will be capable of communication to a variety of PLCs and I/O hardware systems, you just need the flexibility of connecting them using one or more of the 3 mentioned above.
Now if what you were asking about was a "low cost" SCADA system package to use, I would be very wary of going that route. Most of the projects I get involved with that used a "low cost" solution are, 5 years later, ripping it out and replacing it with one of the major players. It is difficult and expensive to maintain a software company, only the very largest and very smallest can hope to survive. Smallest (one man shows) can offer up-front lower cost products, but can be a support problem if you are not in their back yard. Larger companies, i.e. Wonderware, Siemens, A-B, ABB, GE etc., offer continuity for the long run and are often lower cost over time.