Transmutation stones (lvl 1-79) and crystals (lvl 80) haven't been around since the April 2014 update, when they merged them into one type, transmutation charges.
These transmutation charges are from:
- Map completion. (City giving 1 charge, explorable zones giving either 1 charge or 1 black lion chest key)
- WvW/PvP reward tracks (4 charges per reward track)
- Login rewards (3 charges every 28 days)
- Gem store
When buying them with gems, you can get them at these prices: 5/150 gems, 10/270 gems, 25/600 gems. Current exchange rate is 25g 12s for 100 gems, so roughly 7g 53s per transmutation charge. 1g is worth 0.08 USD, meaning 1 charge costs about 60 cents. If you were to transmute an entire set (8-9 slots, depending on twohanded weapon or dualwield) you'd be spending $4.80/$5.40 worth of gold on one set. Or you could explore a city 8-9 times.
There's nothing better about it, it's completely worse than the prism system, it's probably the worst in any MMO. To me, the rest of the transmutation system only barely makes up for it.