I don't understand what you mean by 'tickling DVDs.' Do you mean like stuff that is mainstream like things that are actually on TV or fetish films from producers?
If you meant mainstream TV you're fine with just buying say a season or collection. Fetish films definitely require more thought, but if you are the administrator on your computer/control (history options, recent, etc.) you might consider purchasing downloadable clips.
Either way, if discreet is the way you want it to be kept, not sure if this is legal, buy the DVD; get it sent to a post box, then rip all the DVDs onto your computer and resell the DVD on Ebay. If you consider ripping the DVDs, my advice would be to back up the content of your DVDs and computer to a portable hard drive. I highly doubt that your family would use your portable hard drive without telling you, but Administrative functions allow you to do things like put passwords on things. Rinse and Repeat.