If you ask 20 people you will get 20 different answers to those questions. That said, Lowes has a very good selection on thin Oak, Poplar and Pine but you are going to pay dearly for it. I agree with Terry Lee, if you have a saw mill or kiln drier that is the place to go. You can soon pay for a small planer with the savings that you will get on the lumber. Just one caution, if you buy wood right off the saw (not kiln dried) it will take about a year for it to dry to a usable level. Invest in a cheap moisture meter and learn the proper way to stack and block if you are going to buy green wood. Good luck you will get the feel as you go along.