The best way to buy any set top box connection is to compare the channel and budget of the packages that are available on various DTH service providers. Compare the quality of SD and HD services,channel numbers and the availability of your must required channels in the packages.
According to my personal buying experience. I would suggest to visit : Bookmydth.com to compare and buy set top box connections for all leading service providers like Tata Sky, Videocon d2h,Sun Direct,Dish tv.