Another rust removal method we used before getting the blasting equipment.
We used an old bin as some of the parts we wanted to clean were quite large. Mix water and molasses together 9 parts water 1 part molasses. Can be bought in local farm shops as it is used as an additive in feeding. Drop the parts into the mix ensuring the water molasses mix completely covers all parts. Leave for a week, remove and clean by washing and wire brush, place back into mix for another few days, remove and wash it down with a power hose, dry it off and wire brush if you like then coat it in a rust prevention before painting. Something like Kurust just to stop it surface rusting before you can prime it.
Its slightly more time consuming but is miles cheaper and can sometimes be more beneficial in getting into nooks and crannies on parts that would prove difficult to blast