Hi cathye,
Thanks for the link 
… although they aren’t really a bunkie board (which is solid and not flexible and goes over slats on a bedframe) but more of a slat set similar to some of the options that come up with a google search on “slatted bunkie board”. There is an example of a 2" slatted bunkie board with suitable spacing here but it is quite costly. There is also a bunkie board here with 2" spacing that is much less costly. Perhaps the best value option that could be used as a bunkie board I’ve seen is here which is available in a bare “slat conversion” version and upholstered version that can be used to add airflow under a mattress on a solid surface platform bed or as a bunkie board to add additional height or more even and solid support under a mattress (you can see the prices in post #6 here). Even one of the Ikea slatted bed bases here (which has some flex which may change how the mattress feels and performs) can provide good support and airflow under a mattress and are also economical
The slats you linked would certainly work if the spacing was good (and it looks OK based on the picture) but you would need to remove and replace the slats you currently have because they couldn’t lie on top of them.
Phoenix