the prices i remember now (and not too OP):

ancient bathtub--------50k
locker/wardrobe--------150k
mat. cabinet-----------150k
iron material----------3k
alum plate-------------35k
hard alum plate--------55k
steel------------------22k
rubber-----------------8 - 9k
small gear-------------200g
medium g.--------------4k
big gear---------------10k

P.S: theres a shop near the pot in kelan,thats the max OP shop,so dont do a price check there XD