Considering the way the deck functions, I don't think you lose all that much by playing Overgrown Tomb in the Bayou slot, and you lose nothing by turning Verdant Catacombs into Windswept Heath since every fetchable land in the deck is a Forest
In the physical world, you can go to places where buyers are: stores ( my personal favorite was always La Batikueva ), tournaments, places with lots of casual play (back in the day, the malls in Caballito and Villa del Parque), gallery dealers, and open-air spaces like Parque Rivadavia
Volcanic Spite is technically strictly better, but only if battles are involved
Adding more value to him is the fact that late in the game you can transform him and either dig for more resources, blow up any creature/planeswalker or recur something from any graveyard
It doesnt even have to be your creature either
Tallied up, the value on Grimoire is around $52