How high quality can you afford? How high quality do you actually need?
Hardinge, in the USA, still makes MT2 collets. IIRC, their standard grade collets are around the $100 price mark each. If you desire accuracy, they will make higher grade collets for considerably more money. Their accuracy specs can be found on their website.
Are you running them in a spindle that is actually accurate to a level that paying for accurate collets is worthwhile? I have a couple machines that use MT2 collets, and would not be willing to spend the kind of money Hardinge wants for theirs.
In Europe, look for Schaublin stuff too (priced as high or higher than Hardinge, if bought new). I have seen some Schaublin collets with Emco milling machines, so I know that they were available, though they may not be any longer.