And hasn't stopped.
My question is, why?
The card obviously holds a special place in the game's history for both good and bad reasons along with the notoriety it holds because of that. It's the best planeswalker ever printed, and probably one of the best cards ever printed. It's name is Jace, the Mind Sculptor, and Patrick Chapin loves it. Maybe people just decided their Jaces were worth more than the old buylist prices, but that doesn't feel like the whole story.
The only reason I can think of for this price spike is speculation that Jace, the Mindsculptor will be unbanned in the Modern format as some pros have called for.
If Jace was unbanned the internet would go insane again, and most copies available online would be bought out within the hour. Retail outlets would adjust their prices, I wonder if would SCG stop at $150? The exact price doesn't really matter, what matters is the reaction to the unbanning itself along with the new presumably higher retail price.
Part of Jace's infamy will always be tied to the $100 retail price tag he held when he was in Standard, and the feeling of being 'priced out' many players had who wanted to play the format. Why would Wizards want those feelings brought back into the fold for a Modern format without the type of support Standard has? A format they are trying to make more accessible. A format that can't afford that kind of bad press unbanning a $150+ Jace would cause.
Modern Masters has shown us how serious Wizards is taking establishing the format, and shows us the way unbanning Jace could work. Of course, Jace isn't eligible for Modern Masters itself, but some type of artificial supply increase is needed before the card is unbanned to lessen the public backlash as well as alleviate legitimate price and supply issues. That of course brings about several questions that there are no answers to yet: If the supply increase happens, how big will it be and how much will it effect the price? Will it come before the unbanning or after?
The uncertainty that these questions brings make me want to stay away from holding copies of Jace, the Mind Sculptor in the long term, I have no problem acquiring the card in general, but a hold has too much inherent risk, especially when factoring in the initial investment required.