Yes it is. Write %c in the text field instead and put this function into the text editor:
Code:
function ()
local name,_,icon,_,_,_,_,_,_,_,_,_,_,_,value=UnitBuff("player", "Ignite")
if(value > 999999) then value = math.floor(value/1000000) .. "M" end
if(value > 999) then value = math.floor(value/1000) .. "k" end
return(value)
end
123 will still display as 123
12345 will display as 12k
1234567 will display as 1M, which might not be of much interest when it comes to ignite but perhaps usable for other buffs.