A straight forward approach would be digging deep into application notes provided by those major mcu manufacturers like Atmel, Philips, or Microchip.
For example, from Atmel:
Concrete example: Application Note uses the AT89C2051 to implement a simple digital thermometer system.
http://www.atmel.com/dyn/products/app_notes.asp?family_id=604
From Microchip:
A Clock Design Using the PIC16C54 for LED Displays and Switch Inputs
**broken link removed**
Mind you, Atmel's 8051 device is totally different from Microchip's PIC device. However, both of them are microcontrollers at the end. They both do micro stuff like the controller chip of a microwave oven's input panel, display panel of some washing machines, etc.
For development software, you may use assemble language (asm) which would be more difficult to learn but most of asm packages are free. Knowing asm is also the key to knowing hardware well.
If you use C language, you may need to invest on a C complier, depends on which mcu to use. For example, 8051 needs KEIL C complier (costs a lot), but there is also SDCC complier (free).
For PIC, there is CCS complier (US$125 or something), or hi-tech C (US$900?)...
When you have to decide which mcu / projects to work on, choose the one that would be easily available from your country. For example, getting a PIC mcu is more difficult in my place if I am getting it for just 1-2 pieces. Freight cost can be substantial if you need to get every component from overseas. If every penny counts, just visit the nearest electronic store nearby and see what they have. Most likely it would be a AT89C51 or 52, or PIC16F877, or 16F84a / 628...Compare the price, get a cheap crystal and a few resistors, and capacitors to start.
Afterwards, you may also need to prototype circuits yourself. Breadboard for simple projects. For more complicated projects, or you really want to go deep into making electronic stuff, learn using CAD software for PCB design and do chemical etch at home. Again, this won't cost you much and it can be fun, too.
Trust me, digging deep into app. notes provided by the manufacturers won't cost you much except the internet surfing cost, and you can learn a lot, really.
John