Pro and Deluxe are very different products IMO. Although Deluxe is good in its own right, no version of Deluxe can hold a candle to any Pro version. This is due mostly to the use of Solids in Pro and TC Surfaces in Deluxe. Solids just allow so many more operations such as shelling, filleting, lofting, snapping and a whole host of other things.
Can you do the tutorials in V12.1? Yes and no. There have indeed been a lot of changes since V12.1 so one would have to realize that at some points alternate methods may need to be sought. If you are willing to give one a whirl, knowing that you will not be able to go keystroke by keystroke as it is written, but by general principles and processes then you should be okay. You can always email me while working through the tutorial with questions about version differences and I would offer some guidance.
I was checking out ebay the other day and you should see what you can get V14 Pro for these days.