Jenny!
I have never noticed any varying velocity sensitivity of keys, nor have they (even vaguely) stopped working. And as far as prices go: I live in Sweden, and, although Fatar SL880s can often be had at special discount prices, they still are comparatively pricey. However, I don't know how things are in your country.
Where they don't score very highly is in the midi control knob department - but that's another matter...
Anyhow, why don't you try one out at a shop?
All the best,
Magnus