I use Devolo plugs for our desktop pc - ours cost about £70 for 2 (you need 2) but you can get faster ones for more, and you could probably get the ones I have for less online - I needed a quick solution so I went to Maplin.
One plug is connected to our router by Ethernet cable and plugged in to the ordinary electrical socket, the other is connected by Ethernet to the PC & plugged in nearby (they do have to be on the same ring main, so check that you haven't got more than one) It literally worked within seconds, I didn't even have to reboot, just restarted my browser. Since we've had them (about 3 months) they have lost the connection twice, first time I just had to right click the connection icon & click repair, second time I had to turn both plugs off & on again, but it was very quick. It's early days yet, but so far I'm quite happy with them.
I have this one but you can get ones which are twice as fast, ones that incorporate a wireless access point, so ou can use a wireless laptop in the room, and new ones that stream audio. Mine is 85 Mbps, which is fine for me, but I don't do a lot of downloading or watch online video a lot- if you do you might want to go for the faster version.
One big advantage of wireless is that it might not cost you anything as most broadband suppliers will give you a wireless router when you sign up, and modern laptops have wireless built in.
One big disadvantage of plug-in is that (obviously) you need to be able to plug in the equipment you want to use - and (less obviously) as already pointed out it must be on the same ring main. In virtually all modern houses there are at least 2 ring mains (upstairs and downsatirs), with most having the kitchen on a separate one too.
Why not start with wireless, and think about plug-in if you are unhappy with it?
I agree about the wireless probably being cheaper - we do have wireless too, it was only one pc that didn't have a wireless card, we had an ethernet cable going through a doorway & it suddenly became necessary to be able to shut the door (!) & the pc was the one with the shared printer on. So the plugs were the quickest solution.
Maybe you got the idea from the same place I did MrV - not that I know where that was, but I definitely had it in my memory too! I haven't needed to check if it was a problem here because we only have one ring main in most of the house & another for the kitchen & garage.