Save the trees. We have had a number of clients who have been looking for wood flooring and wanted the look of the old wood floors that are in so many older apartments. While new wood can be doctored up to look good and sort of old, there is nothing like the real thing. We didn't know where to go for old wood until recently, when we came across Mountain Lumber. These folks are the real deal.
Mountain Lumber started in the early 70's when Willie Drake started dragging old Heart Pine out of buildings in Virgina to save it from demolition. Today Willie's company sets the standard for reclaiming old wood from barns, factories and even piers, where pilings sticking out of the sand can run as deep as 45 feet down. All their wood is stripped, sanded, de-nailed, kiln dried and cut down to flooring. They even run a metal detector over each board.
Mountain Lumber sells 11 different kinds of wood flooring from Historic Heart Pine to Granary Oak to wood taken from Bulmer's English Cider vats. Prices vary from @ $6.50 per sq/ft to @ $15 per sq/ft, while standard wood flooring can cost you @ $4.50 per sq/ft, which means that this approach will cost you double on materials generally speaking.
But it is an investment (and how many of us have huge floors?).
Also, if you check out Mountain Lumber's site, they are always running sales on certain woods which makes it very affordable. Right now they are selling a number of woods in the $3 to $5 price range. MGR
Another old wood to consider is reclaimed logs pulled from historic log runs and lakes. Lately a lot of this old growth timber has come to market as new methods have been developed to dry the wood out.
I purchased a lot of genuine Mahogany (as opposed to another wood like santos dyes mahogany) from a company http://rare-earth-hardwoods.com/ (check archive.org for old webpages if its under construction) that also sells several species of reclaimed lake wood. I'd buy again from that co. although at the depth, 3/8" for glue down, i ordered quite a few of the longer boards were warped.