We have hollow core, panel-less doors all throughout the house. I priced out hardwood doors and MDF/solid core doors and came to the conclusion that it just wasn’t going to be worth the cost of materials and labor. I would personally love it, but I didn’t know if I could fully recoup the cost in the sale. I believe my quote was around $490 + my labor.
However Home Depot is currently running a special where they will sell you solid core doors for the price of hollow core. The new price was $288 + my labor. Not bad! I went ahead and placed my order. I also purchased a kit that guides you on making the bore and etching the door for the hinges. Very exciting – This Old House actually has a great tutorial if you’re interested.
An example of what I order is below (picture taken from Salisburyblog.com):

