So I probably have a different opinion than most, but here goes.
Disclaimer: I have a BT30 Dyna
I actually applaud IGG for making Dynamica affordable by newly released Dragon's standards. I had saved up enough Magic Powder from Treasure Mining, Catch-a-Prize, Creation Machine, and Tree of Choice over the past 6-8 months to obtain my first two copies of Dyna F2P (relatively speaking). He costs about 2700 Powder per copy, so in order to get him on par with his Legendary Hero counterpart, it takes 3 copies and therefore ~8100 Powder (about the same as other high end P2P Heroes have taken). What makes him more affordable is that Magic Powder itself has become more accessible to F2P players. It's genuinely possible for F2P players to obtain a copy (or two) of Dyna with proper planning. This is also just the first iteration of Dyna in Floating Isle. I'm sure he'll become more affordable as time goes on. To summarize, I personally feel that the entry price point has been fairly balanced.
Now for his mechanics. He is, without question, OP. But what Dragon isn't at release? Skele was. Lava was. Zeph was. Dyna is. But I will yield some ground and say that relative to other Legendary Heroes, he is slightly more OP than most Dragons. This is probably due to his being the first Epic Dragon entry. Currently, there aren't many counters to Dyna around, but he is killable. Making his immunity to abnormal conditions and damage cap dependent upon his total health is the only thing keeping him from being a runaway train. I'm sure as time goes on, more counters will become available (both by Hero releases, and by player experimentation). There's no need to overreact (yet ).
The other thing I'll address is the notion that we should treat Dyna like he needs all 20+ copies at the start, making him ridiculously expensive. I personally like the Relic system. It's something that can be built over time, giving use to the dupes that previously served no purpose. But by no means does Dyna (or do other Epic Heroes) need leveled Relics to be viable. Relics are more of a bonus that can be earned with time, not something to be included in entry price points.
That's my opinion thus far. I'll keep y'all updated.