While the material you chose will, of course, depend on your personal needs, preferences, and budget, you can always save costs by doing it yourself instead of hiring a professional. The Internet has many videos on going the DIY route but remember, do it only if you have prior experience of knocking down existing design and relating a new design. DIY is good only for people who know their stuff; for others, it can turn out to be extremely time consuming and worse, a half-baked project.
Oak and walnut are two of the most common hardwood choices and for good reason. Oak is durable and stains well while giving an appealing natural grain and is reasonably priced. Hickory, maple, ash, cherry are also good choices too so take your time and decide accordingly. If you prefer a light-colored hardwood floor, ash is an ideal option, while people who expect a lot of foot traffic should consider hickory as an option.