You're asking the wrong question for this site. we're here to help you on diy jobs. Your initial question was best suited to an estate agent.
Someone will view the house, and buy it simply because its got a wood burner; whilst others will walk away just because of it, so this is about doing it for yourself, not for the future value of the property.
You've said that you have a gas fireplace, but not what type. I'll assume you have an existing fireplace, but is it a gas fire inset, or in front of the fireplace. Have you stripped it out yet, and checked if there's a flue liner or just the original open flue.
By the sound of Daves comments, his fire was too large for the size of the room, as having installed both a 4kw, and a 5kw model, I found the 4kw burned more efficiently for the size of room than the 5kw did. But his comments were valid. Gas is cheap and controllable, but it'll need connecting by a gas engineer.
It's not difficult to install a log wood burner, and if you've got access to wood then it's something worth considering. Pine isn't great for burning as it burns quickly, and can produce an oily residue, so you need to make sure it's cleaned at least once a year. But the upside, is that you've got free fuel. A log burner stove is about 80% efficient, whereas an open fire is only 15%, but both work on the principle of pulling cold air in from the outside, and then sending the warmed air up the chimney, so if you can pick up a burner that has an optional external air feed that goes to an outside wall, then that's the best option.
It costs £143 for the building control notice. Assuming you've got a hearth, then you first need to get the chimney swept. You use a wire brush on a drill to clean area for the closure plate in the throat of the chimney. You drill and fit the bars for the closure plate, and cut the plate to size. Drop the liner down the chimney (you may need scaffolding for safety purpose) you'll need about 8 bags of vermiculite to insulate the liner, and then a header plate to keep the liner in place, and then fit a cowling with bird deterrents on it to keep the rain out. Then you slide the burner into place, and fit the internal flue. Seal all joints with fire cement (as well as the gaps around the closure plate) fit a CO2 alarm, and call building control to sign it off. Job done.
Having said all that, you don't need to fit a flue liner or vermiculite, but it makes the burner more safer and controllable. I did a tiling job in a fireplace that had no flue liner, and that showed me how easy it was to fit a stove was.
By the time you've taken in to account the building control notice and the scaffolding, you may not save a great deal, but you can pick up some great bargains on eBay, and put in a much higher quality burner than you'd get for the price you've been quoted.
