Come the recession there will be a lot more amateur "business" sellers on Ebay but most of them will not make any serious money. Ebays fees are brutal, and by the time you have paid them, Paypal, and all the other expenses you can be left with very little in your hand.
If you are registered with HMRC all these things (along with a whole lot of other stuff) become "legitimate business expenses", Dealing from home you can claim part of your rent/mortgage, Council Tax, heating/lighting/phone/broadband etc. HMRC even has little recipes set up so you dont have to work it out if you dont want to.