Pro-grade stuff, yes, but you can build decently nice cabinetry out of the affordable Alder or other whitewood boards at Lowes or Home Depot, especially if you're going for paint, not stain. Also, nice birch plywood has come back down to reasonable prices per sheet. (Use edge banding on plywood to give a pro look - it's easy to iron on and trim with a razor knife.)
Part of the trick to doing this on the cheap and easy is recognizing that many times (e.g., bookcases, or cases for cabinets (order doors from an Internet shop) the precise dimensions matter less than consistency between the pieces. I did a bunch of built-in bookcases a few years ago after my table saw died, and had Lowes cut all the 3/4 Birch ply down to about 9 inches. They won't do or guarantee precision cuts, but I just had them set up the saw once and rip out all the strips from several sheets of plywood at once, so all were identical width, which I could then easily cut to length with a power miter saw. I saved thousands of dollars over the quotes I got from local carpenters and cabinetmakers, and the result is very close to what I would have gotten from them. (BTW, another pro tip is General Finishes "Milk Paint", which is expensive, but worth every penny - put it on with a good brush and the stuff self-levels so well it looks very close to a pro sprayed finish, and comes in a wide range of colors.)
Whitewood boards are great and very cheap, but I would still opt for MDF.
Kiln dried whitewood still produces sap and dents easier than any MDF I have worked with.
By whitewood I presume you mean that mysterious asian species of wood, that dominates the market.
Byt here's my tip - for amateur woodworking, go to a speciality lumber yard that sells S4S. They have discounted and returned items at fairly low prices. I made two bedside tables out of warped, cracked oak shelving S4S boards at about 30% of the cost of materials. But... that was still a hobby project that I had spare time for. If I accounted for the average cost of a carpenter's hourly wages - those items would cost easily $2000 each in labor.
