Sanwa has been producing model R/C equipments for a very long time. In the 70's and early 80's it is as popular as Futaba. There is no doubt in their quality but I would not suggest a beginner to buy it for his first R/C. The most important thing is that it is difficult to seek help in the field. Not many people are using Sanwa for R/C aircrafts now. And for the same reason you cannot use the trainer system to link up with the others.
I agree with Stanley: buy a cheap R/C first. When you are ready, change to a 8 or 9 ch transmitter. The middle range 6ch is nearly useless for a six servos sailplane, and you will find a lot of limitations when using it in helicopters.
SkySport does not have mixer, but you can buy a 3 in 1 mixer made by Windrider (manufacturer of the Bee). It includes mixer, low battery buzzer and lost buzzer which I think is a good deal.
Here is the website of Sanwa:
http://www.sanwa-denshi.co.jp