Hi K... Bill & Mim are BOTH right here... you could do just the box and grounding (depending on condition and layout etc) for around $1500 or so. Or you could do the entire house re-wire which could be upwards of $5-7500...
Just call a couple of electricians (this is what I do when I buy property), get quotes and (and here is the important piece) I get their professional opinion from questions I ask and options they give me back...real easy... :)
FYI: Good on you for continuing to look at real estate for your investment!

K.

The cost of converting you electrical system can vary depending on the size of the home scope of work necessary. Our feeling is the work could be done in a range of between $2,500 and $4,500.

We recommend getting several estimates for the work by licensed electricians.

Good luck

Hello K,
It depends! (Don't you love that answer?-- but it DOES!!) Is the house a rancher or 2 story? on slab or with good crawl space or a basement for access to wall cavities? accessible attic?, etc.
Electrical work is certainly a do-able renovation for most houses in our area, and can be a good fix-up investment. And with the slowdown in consttruction you should be able to find a conractor who will take a look at it in a reasonabale timeframe right now.
You might consider putting an offer on the property contingent on getting a satisfactory estimate for work to be done.-- just a thought! :))
Call me with more particulars, and I will be able to give you more information