Put it in these terms, the technology in a digital camera will age quite quickly as new products are released, often enough to tempt people. My D7000, as trusty as it is, is already out of date and will probably require an upgrade in a few years time. This is where the expense of digital comes from, along with the cost of peripherals, computers and legitimate software.
The Yashica Mat, and Pentax Super ME, I have are both close to 30 years old. The technology behind an analogue shot isn't going to change, only the emulsion does. So when Kodak upgrades there emulsion, there is no need to drop ££££ on a new bit of kit, rather a few quid can be spent on a roll of film. I home scan my film, and at the moment it costs me about £8-10 a roll for 35mm, or £15 for MF.
A little price comparison:
Digital:
D7000: £1100 New
Computer: £700 New
Software: £200 (lightroom)
Total: £2000
Film:
Camera Cost (Yashica Mat 124G) - £100, Ebay
Film Cost (Slide + Dev + Scan) = £15
To match the cost of a digital camera, I would have to shoot 1 roll of film a week for the next 2.5 years. That's 1500 film shots.
It's a close run thing IMO, if you scan the image yourself, you are looking at a development cost for MF of about £8. Thats about 4.5 years worth of exposures (238 rolls, 3000 shots). In 4.5 years, the digital camera will be miles out of date (although, for the same amount of shutter actuations, barely used).
Food for thought, I have never looked at it from a cost point of view.
And digital with never replace the feeling of looking at a perfect slide film for the first time.