DIY Sandblasters are available from many Autoparts stores such as superche@p, they are not that expensive & if you decide to paint more then just one set of rims it will pay for itself in no time. An alternative is enquire at powder coaters, they have industrial size machines that use various mediums to effectively sand blast items prior to the powdercoating process. I got a quote in Sydney for $50 per rim in solid colours, so that may also be an alternative to the ghetto diy black paint job. Good luck