I'm posting this from my phone so sorry it looks a little strange! I just found a brand new display of Layla Magneffect polish at my local ULTA! Layla is a higher end Italian brand that until recently could only be purchased online if you lived in the US.
The best part about the magnetic polish is that I found it on the drugstore side of ULTA. This means if you have a coupon to get the $3.50 or $5.00 off a $10 purchase it will work! (Which is not true for Butter London. )
