Writing on 125KHz Tags

I am working on a project using 125KHz tag as an access control.
the target users includes considerable number of socially disadvantaged people.
Since tag cloners cost about the same as tags, likelihood of some tags being cloned is greater then the likelihood of none of them being cloned.
Mine intention is to pass people re-writable tags, which will keep changing their content when used, so that any copies made becomes pointless...
While I do like Rdm6300 which I am using for now, it is a temporary solution during development.
Could anybody point me towards solution (board or IC) towards a solution enabling me to program the re-writable 125Khz tags.
I am aware of the possible issues if copy is changed (and made provision for that occasion)
RW tags are easy to get