Considering that that the green member of the M20 cavalier cycle - Cavalier of Thorns - is currently pushing $20, there is probably still room for Cavalier of Flame (planeswalker stamp) to grow, although right now the green Cavalier shows up in 14% of Pioneer decks while the red one is in less than 4%, which means it's going to take a lot more play for Cavalier of Flame (planeswalker stamp) to get anywhere near Cavalier of Thorns price
If you manage to transform it for a whopping 9 or 10 mana, you get an even better 11/11 with trample, indestructible, and damage with poison counters
Beyond these, the rest of the build is cheap and cheerful
I hate to say it, but being cool is not the same as being good
San Francisco police released an arrest video showing a transaction for Pokmon cards that turned violent on May 28 around 3:16 p.m
Card Kingdom also has an excellent buylist, and its a great tool to browse through and see what you could send their way without having to list everything you own first