If you can fabricate single-sided circuit boards at home you can build this digital oscilloscope. It uses mostly through-hole components with just a couple of surface mount chips to contend with.

Both oscilloscope channels are protected for overvoltage up to +/- 50 V. The FPGA samples at 100 Mhz through a 10-bit dual analog-to-digital converter ... with short circuit and overvoltage ...