As a beginner I would avoid finance. A working used Yamaha digital can go on almost forever. Don't pay too much, and don't worry about sound quality as headphones externals speakers on just about every Yamaha are OK. Worry more about what it feels like, do the legs come off easily, etc. A Midi interface and PC, will get your Yamaha more flexible sound than a new Yamaha, but you don't need that, it is all a distraction from learning to play. I have never owned a Yamaha, but have an old Roland I bought s/h. I would say you need a minimum level of build quality, and Midi, nothing more. Yamaha of any age should do. A Korg or Roland used is also OK. I would say pay no more than 2/3 the price of the new gear4music in your link, ideally under half.