Drums suckin it up, stupid creaking noise Options

[tcox22]

so recently i've been noticing my rear brake drums have been making this really abnoxious creaking noise everytime i stop. i've gone to my mechanic and all he said was that the noise is being made by brake dust. so i decided to check myself, i took the drum off and got all the dust out and then put them back on... same noise. i wonder if maybe it's because my shoes and drums are rusted badly, that's why the noise is happeneing. I eventually want to do a disc brake conversion in back, so would this be a good time? would it be cheaper and easier for me to buy 4 new rotors and 2 more calipers and pads and then do the conversion instead of buying new parts for the drums? and for the people that have gone this route, how much money and i looking at spending? thanks.