Cheap Midi Keyboard without a PC?

I've recently created a midi keyboard and now and then use it with my laptop via FL Studio. Now I wonder if I have the keyb. Even without the laptop can use, as it annoys me, this always up. Practically, a device that is about the size of a pack of cigarettes could convert midi inputs into piano sounds and cost no more than 60 euro. In addition, my Midi Keyboard ONLY has a USB port. This point should also be considered. LG and thanks in advance.

With only USB to MIDI it looks very bad! Otherwise there might be a possibility.

Okay thank you very much!