Hi. I know this isnt a normally sought after product but im looking to buy a
משנה ברורה ביצחק יקרא חלק ד. (just the 4th volume)
Its part of the blue feldheim set with Rav Nevintzal's psakim
any leads would be great
Most seforim stores wont break a set, so you are out of luck in most places (I actually have that set of mishna berura and 2 chelek vav's somehow and would gladly give it if someone needed it).
Capitol Seforim in lakewood is a second hand seforim store, its a good store for that type of thing but seems a bit far from your location.