Is anyone using this type of product? If so, which ones are you using?

What's the least-expensive manufacturer out there?

Thanks!

The least expensive manufacturer is anyone who makes double-knit fabric with an artsy pattern. Make your own grille frame and stretch it.

But do you mean you want grilles that have artwork on them, or that you want what seems to be just artwork but that also emanates great sound?

When I worked in Loudspeaker Engineering at Marantz in the very early 80s, we had a model with a grille cloth of double-knit with a wood grain print on it. The physical design was so clever that people would walk around the speakers and ask how the sound got out. The company was so phenomenally screwed up at the time that we only sound a couple hundred of that model. But THAT was grilles with artwork on them!

I believe Monitor Audio does this, price is up there I'm sure. Probably an expensive option no matter who you look at...

This:

http://www.artcoustic.com/

I'm not looking for speakers, just some sort of artwork looking pictures that can be hung on the wall to cover some existing inwalls, that still allow sound through.

its not going to be cheap. I found this place

[Link: acousticgeometry.com]

and this place:
[Link: acoustimac.com]

the only problem is its "printed" so its going to look like a weird cheap piece of art. I spent hours on researching trying to conceal some speakers in wood. Decided on a highly specialized paintable acoustic cloth. Will finally see how well this will turn out in a few months.

Unless your speakers that are already in the wall are expensive you might be better off just using something premade from monitor/artcoustics.