HI. fm1234 is right. At the rate in which new electronic gadgets are being produced, you won't be able to depend on that to produce income for very long..I remember when the first xbox came out and everyone was rushing to find a supplier for them, but you can hardly give them away today..
What you should try to do is have about at least 3 streams of incomes and/or products. That way if one suddenly dries up or you loose your supplier for that stream or item, you still have income being produced by the other two while you search for a replacement product for the one you lost...It's the old 'don't put all your eggs in one basket' thing..
The internet market place changes at lightning speed and you have to be able to adapt and change on the fly to keep up, so try and make your stragety a 'plan ahead' type and you should be fine...