The Knights Templar were undoubtedly wealthy at the height of their power, but the idea that there is a huge 'treasure' to be found is almost certainly an invention dating from long after their dissolution. Their wealth consisted largely of land holdings (including the entire island of Cyprus at one point), along with sources of income derived from what amounted to an early form of banking: not the sort of thing you can bury. Like most wealthy organisations and individuals later, they didn't keep their capital tied up in valuables, but instead invested it. And given the methods used by Pope Clement V's inquisitors, I suspect most assets they had hidden would likely have been revealed under torture (if you can persuade a Templar to 'confess' to spitting on the Cross, getting him to tell you where the loot is buried should be a doddle...). Maybe there are a few forgotten items of Templar property hidden away somewhere, but any value is highly unlikely to amount to much in comparison to what the Templars held overall, and such artefacts, if they exist, are probably worth more for their archaeological significance than anything else. A horde of Templar treasure lying hidden for centuries makes for an entertaining story, but as a historical concept, it makes little sense.