Seems to be really common in this scene - though I'm surprised G-Werks has gone. I thought they were netting the guys with deep pockets?
Either way though, things are really tough for tuners etc at the moment. It's one of many reasons why the mags are closing down - the advertising money isn't there. People are either cutting back on what they spend (including advertising) or going bust (in which case, they're not advertising either). That's why it pays to be a niche mag like PVW - niche mags attract niche advertisers, so you're pitching to a very specific readership.
A lot of the problem is, as well, the "scene" is that much smaller these days. It's not seen as very cool to be buzzing around in a modified car, even if it is running flashy wheels and a £5k paint job. That's not to say it's died altogether, but it's gone back to being a small scale hobby and even out of that small group not many people do big money projects any more. Wheels, a few colour highlights, some stickers and a lowering kit.
I don't think all of the above is recession based either. It's been heading that way for years. New cars don't help - they're leaving the forecourt with decent wheels, stereos and all the bits they need nowadays.
Sad times, basically.