Usually you will want to place an Aura on the best creature for it and leave it there
What you really need to look at are the recently sold prices
I personally would be willing to pay it to avoid some of the adverse effects that can accompany A Whole New World (like allowing them to draw into a Be Prepared)
By incorporating ink acceleration, the ink curve is calculated to smoothly connect to your 7-cost finisher

Daretti and Artifacts Engineered Explosives | Illustration by Lars Grant-West Commander (1) Planeswalker (2) Karn, the Great Creator Ugin, the Ineffable Creature (9) Goblin Engineer Goblin Welder Imperial Recruiter Lodestone Golem Magus of the Moon Metalworker Phyrexian Revoker Silent Arbiter Walking Ballista Instant (7) Abrade Chaos Warp Deflecting Swat Fork Pyroblast Red Elemental Blast Thrill of Possibility Sorcery (8) Anger of the Gods Gamble Rolling Earthquake Scrap Mastery Shenanigans Trash for Treasure Wheel of Fortune Whipflare Enchantment (2) Artifact (40) Arcane Signet Basalt Monolith Clock of Omens Codex Shredder Crucible of Worlds Cursed Mirror Cursed Totem Damping Sphere Engineered Explosives Ensnaring Bridge Fellwar Stone Grafdigger's Cage Grim Monolith Ichor Wellspring Krark-Clan Ironworks Lion's Eye Diamond Lotus Petal Mana Vault Memory Jar Mind Stone Mox Diamond Mox Opal Mystic Forge Planetarium of Wan Shi Tong Rings of Brighthearth Sensei's Divining Top Sol Ring Sphere of Resistance Staff of Domination Static Orb Tangle Wire The Ten Rings Thorn of Amethyst Thran Dynamo Torpor Orb Trading Post Trinisphere Voltaic Key Welding Jar Winter Orb Land (31) Ancient Tomb Arena of Glory Arid Mesa Barbarian Ring Blast Zone Blinkmoth Well Bloodstained Mire Buried Ruin City of Traitors Command Beacon Crystal Vein Gemstone Caverns Great Furnace Inventors' Fair Kher Keep Mishra's Workshop Mountain x10 Prismatic Vista Scalding Tarn Strip Mine Wasteland Wooded Foothills This Daretti deck is all about a slow pace with artifacts like Trinisphere, Magus of the Moon, and Engineered Explosives

If you use a normal counterspell on a demonstrate card, the original spell wont resolve, but the demonstrate ability can still resolve