I would like to add a couple of other points to Bruce Mís comments:
Since you will probably be seeking the advice of a licensed electrician, it might be a good idea to have him evaluate your whole house before you buy it. Older houses often only have 100 amp service (or less) to the main panel. If so, your proposed dryer installation could overload the main, especially if your house has central air. C/A will have a maximum draw of 60 amps, the dryer, 30. Thatís a total of 90 amps. Since you are adding an electric dryer, you must have an electric stove and maybe even a water heater, which means another 50 and 30 amps respectively. Now youíre up to 170 amps! Of course, they probably will not be at full amp usage at the same time, and you might get by, by only using the dryer at certain times when the C/A is off, for example, but sooner or later, especially if you have a family, someone will plug in a toaster or vacuum and the house will go dark. AND, if your older house uses fuses instead of circuit breakers, youíre going to have to buy new ones (fuses) and keep extras around for such a moment. It can be a pain.
Newer houses have 200/250 amp service, which accounts for modern electrical usage, including central air. Even if you do not have C/A, you may want to plan for it in the future. Upgrading an older home to a 200 amp main should run you under $1000, depending on work involved and the area you live in. Donít settle for under 200. Also, the supply lines from the street to the house might not be big enough to support the larger service, and depending on your municipality that upgrade may be the responsibility of the home owner.
Having an electrical evaluation BEFORE you buy is the best bet. The qualified electrician may also uncover some creative wiring done by previous owners which is dangerous, and any work needed could be used as a bargaining chip when negotiating for the homeís purchase.
It all starts with the panel. Just about everything else can be added/modified at a later time, when funds become available. As Bruce M stated, the grunt work is in the wire laying, so if you can find an electrician who will work with you, a little sweat-equity on your part can cut down the cost. An electrician may be more willing to work out a deal if he knows that there is more work down the road.
And last, get the proper permits/inspections. If you have (God forbid) a fire or something, your insurance company will check for the permits before they decide to pay for the repair.