Rather than adding expensive cards just to increase the price and have a "non-budget build" of the deck, I'd just keep playing it as is and adjust the sideboard as necessary based on how the Zendikar Rising format develops
Graded Population Report: Rattata #66 Visualize the distrbution of grades in the chart
But if theres one thing I really want to single at as my favorite thing about the format, its the Saga Creatures
Firkrag notably provides additional value for goading, as whenever a creature deals damage to one of your opponents, if it had to attack such as through a goading effect, you can put a +1/+1 counter on Firkrag, drawing a card in the process

This initiative will kick off with the Secret Lair Drop Series: a collection of seven unique set drops that Wizards calls a love letter for its fans. IGN is excited to give you the first look at one of those drops an adorable cat-themed set aptly named OMG KITTIES! Flip through the slideshow below to see all the cards in this drop , and read on for more details about Secret Lair, the next drops, and more: Wizards Product Architect Mark Heggen told me they built Secret Lair from the ground up to be a home for the stranger, more experimental, more unexpected cards that we think some players will love but dont fit into our sets and other products. None of the cards in this first batch of drops are new, drawn instead from previous sets throughout Magics history, and they wont impact the competitive landscape