My vinyl lattice still looks like new after 20 yrs.

The downside to all ready-made lattice is its thinness, which makes it look cheap. A second negative feature is that it is often installed with no frame surrounding the lattice panel, again, making it look cheap. A third unsavory feature is the too-close spacing of the lattice boards ... making it, guess what ... look cheap. A 5 or 6" stick spacing usually looks better. It amazes me that people are so willing to use the prefab lattice with its inferior look when decent lattice is so easy to make from scratch. With custom lattice, the design opportunities open up well beyond what could be achieved with prefab material. (Explore Chinese lattice designs for inspiration, though simple rectilinear configuration lattice surpasses the look of prefab.)

The simplest versions can be made with 1x2 or 2x2. If it is painted prior to fabrication, it is surprisingly long lasting. I've used painted, untreated wood in some instances and found it to last many years. The painting process can be set up assembly-line style and it goes rather quickly. Cut ends can be quickly touch-up-painted after fabrication. Where the back side doesn't show (as it wouldn't enclosing a deck underside) the lattice itself can be assembled with a single 6 or 8-D galvanized nail driven through each intersection, and bent over with a hammer at the backside, locking the boards together as if a nut and bolt were used. However, it's a much more inexpensive fastening system.

Whenever repainting is needed, it can be done quickly and easily with a mini-roller. If an individual stick gets broken, it can be replaced, making the panel as good as new.

There is another downside to premade lattice panelling that Yard missed - it is almost always configured on the diagonal. To me, that is a dead giveaway that it is prefab........and therefore cheap :-)

Lots of DIY how-to's online.

Your smaller independent building supply yards can get the lattice that runs on the x and y axis and not diagonal, since I agree w/ gardengal that the diagonal lattice screams cheap. And picture framing it with 1x or 2x lumber keeps it straight and true, and gives it some depth.

Thank you @Revolutionary Gardens. That sounds like a great solution!