Buy this small box, SX-150 as a do-it-yourself kit, for only 45 USD. You even don't have to know the art of soldering since it has a very basic scheme. Envelope is performed via an attack/release rotary knob, it has resonant low pass filter, and an LFO. Pitch is solved with this pen-like pin, and it even has a built-in speaker. Order it immediately.

Toy legend from Casio, VL-Tone can be a hero of the home setup again: for 40 USD you can order a MIDI interface for it, as a DIY kit. It performs a standard MIDI In jack - you can set a receive channel and the instrument gives its unique, lovely sound after the appropriate Note On codes. An activity LED shows the valid incoming MIDI commands. To have it, go here.

Making of a drum synth is the title of a new blog - if you follow it you can build your own analogue drum synth. Try it.

Choose QRS Music's PNOscan, and you can MIDIfy you acoustic piano. All you have to do is inserting this lane under the keys - it does not have any mechanical part just pure optic sensors. There is a solution of course for handling the three pedals, too. You don't need an expert to install it, they say it is really a child's game. All the official info can be found here.