I just pay for my HP103 today, it costs me $US 2080, believe it or not, it is the cheapest price I can get it from Melbourne (I think price in USA & UK are always cheaper than Australia
Even Casio PX-100 cost $US 1000 here in Australia, that's why I rather pay more for a better digital piano for the next few years
During my search of piano, I've tried Casio PX-100 and PX-300; I think the sound of Casio as fojae mention are not as good as Roland or Yamaha.
A few points about Yamaha (which I have struggled to make a decision for the last few weeks).
Yamaha (no matter home digital piano or stage piano)
- has a heavier action
- has a brighter tone
- has a lighter action which in most opinions(all the sales person in different music store in Australia who play piano for years) are more close to a real grand piano
- has a more mellow/soft/european sound compared to Yamaha
In my opinion, I believe Yamaha and Roland both are top of the range equipment, so either way, you won't go wrong and should be happy with the purchase. If your kids still play piano in the next few years, maybe you should consider by a real acoustic piano as no digital piano can give you all the control/actions/feels/sounds as a proper acoustic piano.
However, I think if you can spare the few bucks (believe me, I use my credit card to pay for my ~$2000 Roland HP103 and I have no more cash than you), get a home digital piano instead of the stage piano will be better for your kids, as it has the proper foot pedals which may motivate them to get the piano course more seriously. Also, the stage piano (such as Yamaha P60, Casio or even Roland) do not always come with speaker or come with a "not-so-good-quality" speaker, which may not give you the ideal sounds.
As I am an adult beginner who "just" purchase a digital piano, my comments may be wrong, you should always go to the local store and listen the piano and let your kids help making the final decision.