You mean a keyboard controller to control samples inside a DAW sampler like the EXS? Or are u lookin for a something that actually samples and has keys like the Fantom?
If u just need a controller, theres infinite options. M-Audio shits always real affordable and offers a good amount of assignable knobs and sliders but I personally dont like the quality of their stuff usually, however its hard to beat at the price they offer most of their controllers.