I've used an indoor clothing rack for the whole time that we have lived in the condo and paid our electric bill so I used an appliance calculator to find my savings. If that calculator doesn't have the same hydro price as your area then you may want to search "appliance calculator" on a search engine.
There are only 2 of us in the household and we don't really do a lot of laundry - I work at home and DH wears his office clothes twice before washing - but I still calculated about $8 a month. I think this amount would actually be higher because we have an old dryer.
The other cost that you can't calculate with this is that your clothes last longer when they're not put in a dryer so you won't have to replace items as often. Some people say they have to iron more but I've never had this problem. If you shake the clothes out really well before hanging and "hand-press" them on the hanger they seem fairly wrinkle-free.