Suggested for all skill levels and all ages, especially for teens and adults
 
One of the best keyboards on the market, this instrument will serve you for a long time during your piano studies. The cost is justified because Yamaha is a highly reputable brand (so it's a quality instrument), and it includes weighted keys. Without going into too much detail, this feature makes it feel like a real piano and will allow for a better dynamic range. It also includes a sustain pedal which many pieces in the piano repertoire necessitate. For affordability I didn't include the full setup in the link attached to the button below (with keyboard stand and piano bench), but if you'd like that version look here.