Hi , the less sounds and widgets a keyboard has , the more time ( and room ) the makers have for making the piano sounds brilliant.
Personally I enjoyed playing on 100 euro piano's as well as 2000 € piano's ( NOTE : real piano's , old pieces)
In electronics it's a different story , you pay a lot for the software and the engineering behind the product. How the keys act , and mostly how the stuff sounds ! The soundcards of digital piano's with 5 sounds vs keyboards with 300 sounds is way more advanced and gives a real impression of how it sounds in real life
You can find good sounding piano's for 500 € , electronic or real. Sure it won't do if you are a classical student in a music university or something , but for normal people it does the deal , you can make brilliant music on it. Everyone saying that it's all junk or bad is ignorant and are just defending their own material.
Go for something which sounds good to you , and which feels good. Def go for weighed keys and 88 keys. FOr the rest , ENJOY. You don't need tons to make good music ;-)
If you want it cheap , you can go to a MIDI keyboard.
88 weighed or semi-weighed . this way you buy only your controller , so it's pretty cheap because you don't need to buy the software along. I have one from M-audio (prokeys 88 I think) and it plays pretty good for the 100 € I payed for it. The sound I get with contact 5 and Giantpiano on my laptop
Connect it to you computer and get software like Contact5 from "sources" ...