There are in fact some magic activities in Barcelona next week. On Monday 28 you might want to visit the weekly magicians meeting at SEI magic club. This is highly recommended since you'll be able to meet some of the best close-up performers in Barcelona.
On Tuesday 29, Arsene Lupin will be performing at Espai Brossa. This is a tiny theatre and it sells out pretty quickly.
On Thursday 31, Arsene will be lecturing in SEI.
Isaac is perfoming every Saturday night in Teatro Llantiol. Please bear in mind that Sunday is daylight savings in Europe and time forwards and hour.
Anthony Blake's mentalism show in Arteria is black on Mondays and Tuesdays.
In El Club de la Magia there are shows every week from Wednesdays to Sundays.
Regarding shops, El Rey de la Magia and its museum is one of the oldest in the world and it's worth visiting. More modern magic shops are: Magicus and Selecciones Mgicas.
Hope this helps.