ShagMan --
I've purchased quite a bit of equipment from eBay, online supply stores and locally. All using my bank debit card. I used to think about this when I first started several years ago but .... there comes a point when you are spending more time inventing crazy '24' scenarios, imagining Jack Bauer running after you etc etc etc. Fact is, buying supplies is completely innocuous. I regularly use my bank debit card at the local supply store and never think twice about it. I was just there yesterday purchasing dirt and a very straight-laced person comes in to buy nutrients. There are many many many people out there that use the same hardware to grow ... orchids, flowers, even tomatoes. Despite what you see on the news, in the media, in movies -- there is no database mining program to find people growing dope through purchases on eBay. Personally, I'm more worried that the hardware I purchase on eBay won't work (happens all the time) more so than me being tracked from purchases at the supply store.
BTW -- If you want a solid supplier that has an awesome online store, check out Better Grow Hydro at
Hydroponics | Hydroponic Supplies -- great store, awesome prices, just gotta wait for shipping. Good Luck.