They need to drop the price of Win 8.x Home to $50 USD or less, I'd personally say $35-$40 USD. this would get more users to try it, might even get some of those later XP machines to switch, but all they are doing by keeping the price high is getting those people whose XP is about to go EOL a reason to be looking at Chrometops and Android tablets, dumb move MSFT.
It's true that the migration path from XP seems unnecessarily complicated and expensive.
I think that upgrade licences for Vista, 7 and 8 have to bought. Obviously, there's not a lot of hardware running XP that will actually run Windows 8 but still a single upgrade licence (and software that would actually upgrade inplace) would be an encouragement.