Sorry, but even with huge willpower, and much time and patience, it really is impossible. In any case, you'd spend much more on the bits than you would on a new receiver!
To proceed, you'd need: a satellite tuner; if strip and demodulator, mpeg decoding chipset; maybe a cam socket for decryption; control microprocessor (choose one, then write complete software for it starting from scratch!); power supply (the easy bit!); design and build a main circuit board, paying particular attention to rf techniques. So, you see, it really can't be done, it takes a big team of people quite a while (and you'd need a huge electronics workshop)!
In West Europe, satellite receivers get increasingly sophisticated, and older types are now sold at low prices. As you have Internet access, use it to look for these, that's your best bet.
NB, if you have a computer, then some receivers are actually plug-in computer cards (see other threads, this website), but they're no cheaper than standard types.
