I have no clue. Is this exterior or interior , I need pictures of what you are thinking. IMO fake beadboard is not one bit better than shiplap but I need a lot more info.

Sophisticated Beach · More Info

How do I get this look of the wall paneling for less on 9 ft walls?

I re-designed an antique shop where there was an installation of 8' paneling and then a bridge of paneling to the ceiling to complete the height of the 10' wall. Between the upper and lower panels a 1/2" gap was left. We painted the walls Crisp Romaine and the gap copper. You could also cover any line or gap between the 8' lower panels and the 1' upper pieces with some trim or crown.

“I don't care for the horizontal shiplap bc I think it is too trendy.”

So are the vertical beadboard planks you are thinking about. Super trendy. And an affectation. I think you’ll regret them within 2 years or less.

Bead board is so NOT trendy. You could also consider a wider (5 or 6 inch) V groove which looks like your inspiration picture. This is a timeless material. For a nine foot ceiling, I'd probably use the real thing and not the MDF boards which only come in 8 ft lengths. IN using the MDF you'd need to get creative with a wide base molding and wider crown treatment to make up the difference. It can be done.