where's a good art supply store around the neighborhood?

I don't know of one in the nabe. Try Apple over on DeKalb and Washington, the Pratt Institute bookstore on Myrtle near St James, or the art store on Jay Street at Wiloughby (near Sid's Hardware).

in the nabe next door, there's a small one with oil paints etc
It's on Fifth Ave, east side of the street between Berkeley and Lincoln
http://www.smalltownbrooklyn.com/parkslopeN/northsouth/5thave/5thave3.html

I usually take the Q express to Canal St for Pearl Paint . .

b48 to the pratt store often solves our needs without inter-borough travel.

a little further but quite good is
Artist & Craftsman Supply 718-782.7765
761 Metropolitan Ave (between graham & humboldt in williamsburg)
i originally found them looking for wood panels online: http://www.artistcraftsman.com/

if you are going to pearl, i'd also check out Soho Art Materials at 127 Grand Street (between bway & crosby), small yes, but excellent stock

and honestly even though i lived a block from pearl for 25 years i found they went so far down hill and never had anything in stock that for years i have been ordering from ASW: http://www.aswexpress.com/