Let's do some quick analysis...Assume you shot 100 photos in a day. Just using prices based upon ads in the Sunday newspaper, that is about $7 in film and $25 in processing cost (SF Bay area chain drugstore photoprocessing). $32.
Let us also assume $300 film SLR vs. $1300 dSLR...$1000 differential to be offset. That is only 31 days of shooting 100 photos a day! OK, so we have prints vs. no-prints in that analysis. So I would end up spending $19 per day to print all of my digital photos at the same drugstore...differential is $13. So in 77 days of shooting 100 photos and getting prints of all photos, the film+processing costs have equalled the dSLR cost of higher initial investment. Any more shooting that that, and digital is less expensive.
"Wait", you say, "I am not printing every photo"... in the case of film, you would be printing every color neg simply to see if a photo is worth enlarging or not. Or "shooting color slide, I don't have printing cost", but there is the greater processing cost per roll, plus the higher expense per roll of slide film. Yes, you can do color slide processing yourself, but the theoretical savings is lost when you do not process the full number of rolls of film before the color developer has oxidized and depleted itself and you go out to buy another color processing chemistry kit.