There are 3 different major varieties that are sold as pine. Fir or spruce is often sold that way. Real white pine or southern yellow pine are a lot better, in my opinion, but you have to know or take a good guess about what you are buying.
I just ran out of shellac today and went to a mass merchandiser that was not a home center to buy it since I was there anyway. Theirs had been subject to some damage in transit and the date on the bottom of the cans were illegiable. Shellac only has a shelf life of about 2 years but Zinnser's says that theirs is good for 3 years. I try to buy shellac that is reasonably fresh and bought some at a true hardware store that was made in January of this year. The mass merchandisers usually have better prices for denatured alcohol in the pharmacy sections. The difference may not be worth chasing around for.
The stain products, except for the pure dye stains, are readily available at many places. The dye stains are available at specialty woodworking stores or via mail order. Try www.rockler.com. Unless I have a big project, I do try to stay away from these because of their short lifetimes after mixing. I'm lazy and do use Minwax for most things, even though I do have some issues with it.