You might not need a full "set going up to 50", just a few appropriate smaller ones and one at 50. Jim Von Baden posts a list of sizes for the GS iirc.
My Halfords Professional kit goes from T20 to T60 (male) and E8 to E20 (female). It's the only kit I've needed for the past 15 years. They do a torx socket set for £20 but it only goes up to T40 and they don't seem to sell the T50 individually, though it might be worth going to a store and asking them.