Design a FPGA based Oscilloscope
1 MHz is slow enough that this should be doable without a FPGA.  Perhaps you may want to use a external A/D or sample memory, but orchestrating all that should be possible with just a decently fast microcontroller.

Some of the dsPIC 33F have built-in A/Ds that can sample at 1 MHz, if I remember right.  You don't typically need lots of bits for a oscilloscope, since the user will adjust the gain and offset to zoom in on what they want to see.  Entry level scopes don't have more than 256 pixels vertically anyway, so obviously aren't showing more than 8 bit of information per sample.  The 10 bits the internal A/D of a dsPIC can do should be sufficient.