buying from ebay doesn't affect the industry directly as someone else said, the sellers have to source their kits from somewhere in the first place
i.e the makers get paid.
however, this is where one problem, comes into play.
we have no idea where/how some of the sellers get their kits.
you might've noticed that quite a few sellers of tamiya/fujimi kits are based in hk.
now if you know hk like i know hk, then you'd be aware that it is the centre of one of the worlds largest smuggling/counterfeit/stolen goods operations in the world..... make of that what you will....
ignoring this and assuming that everything is legit, because we are buying kits from abroad, in the case of HK sellers, we are by-passing a hell of a lot of tax, hence the relatively cheap prices. also, the way they work
i.e mass storage of kits, operate from a pc (i.e no overheads) adds to the lower costs of running their operation which translates as lower cost to the buyer.
what this ends up meaning is that the smaller, private run model shops on our shores are losing a lot of business and closing, simply because they can't compete with the bare bones operations of the internet seller.
since i started building/collecting kits around a year ago, i know of two shops that have closed while modelzone seems to be opening more branches.....