If you want surround sound, you'll need a suitable decoder, with the additional amplification and speakers. Some manufacturers, such as Yamaha and Kenwood, sell all-in-one boxes which act as conventional hi-fi amplifiers, but also have built in surround sound decoders and the extra amplification required to drive the surround and centre speakers. These start from £400.
Average PAL films cost £25, and NTSC $35. Expensive, but bear in mind the unsurpassed video and audio quality, the exclusive collectors' editions, and the fact they never wear out or need rewinding. Those collectors' editions that include audio commentary, additional documentaries, collections of stills, and footage not seen in the cinema weigh in at between $50 and $150.
Clearly you've got to be a bit of a film anorak to want to watch the same film over
and over again and insist on the best quality. But if you like films, you will.