Ideally, music students should be learning to play their music on a piano, not a keyboard. There are good reasons to consider an electronic instrument instead, however. Weigh up the following possibilities before you choose which investment to make.
It might take a little while before a parent can clearly discern if her child is going to stick with his or her lessons. For the first little while, buying a simple electronic device is more economical. This gives your child somewhere to practice fingering while also learning to read music. A keyboard without weighted keys costs less than $100 and can be rested on the kitchen table. Better, costlier ones offer extra features. But even if a student decides to give up on taking lessons, he might occasionally try replicating songs here or just have fun with the different sounds. I did this long after my lessons ended. And I still do.
Professional keyboards featuring weighted keys are a lot heavier than lightweight, cheap ones but still portable. They can cost in the region of $2,000 although a decent used one might sell for about $600. These instruments provide the advantage of being compact. One can purchase a stand and place the device anywhere that's convenient. It can be moved to a different spot when visitors arrive or you move house. Electronic features allow the pianist to change sound quality so the notes are tinnier, more mellow, bell-like, and so on. Pedals are connected by wires to simulate piano-like effects. Electronics are battery-powered.
The Real Deal
An upright piano starts at roughly the same price as a new weighted keyboard but prices generally rise from there, unless you find someone locally who just wants to get rid of theirs. Check the local papers and Facebook pages and places like Craigslist where you can sometimes find a great deal.
While the electronic ones don't require calibration, the real deal must be tuned after moving and then at least every year, preferably more often. In other words, buying it is only the first expense. Real pianos take up plenty of room and moving one into a house can be a terrific challenge, particularly moving it without damaging the instrument or anything else. You will need two or three strong people, a rolling platform, and a ramp at your front door to get it inside.
Then again, nothing recreates the exquisite sound of a piano completely, nor the feel of sitting at one. I speak from personal experience and preference. A small spinet I had about 3 years ago took 3 of us to get it into the house. The square grand I was gifted recently took a professional moving crew that specializes in heavy moving.
Sometimes the choice is made for a person by finances and location. A piano might not be in your price range, but a student still strengthens his fingers while playing on weighted keys. When one lives in a high rise or a second-story house, getting the thing inside might not be possible without hiring special equipment. Even if a person could get this considerably large piece of "furniture" to the correct floor, how is one to move it through the door? That will pose a challenge unless there are double doors or doors can be removed. Only a keyboard of some kind will be practical in this setting.
For a pupil to excel at playing, he has to strengthen his fingers, not just learn the notes of a tune. Eventually, he must find some way to access a real piano. He might be given permission to use one at school, church, or a supportive family member's home. Keyboards can be distracting with all of their buttons, but with a piano one is inspired to get down to work.