The current categories are few, but they offer good housing for a number of topics. I thought something like "buying experiences" might be useful if members shared their experiences with certain sites or even businesses/vendors. I think many of us use Amazon, eBay, Craigslist, as well as major retailers like Best Buy, Costco, who have frequent sales on shavers but also shaver accessories. And the manufacturers' websites often have sales on new items cheaper than retailers. (I recently dealt with Philips directly and they gave me a far better price than any retailer and upped my shaver warranty).
The potential downside, though, might be it could turn into a "gripe forum" with businesses/vendors perhaps complaining that forum members are giving their business a bad name if they experienced a negative incident.
I guess your own thoughts on this might be more useful as you've had a lot of experience. I think the bottomline might be establishing a forum category, and see if there is enough interest among members, since guests can't contribute. If not, you could always drop it.