damn, what a bitch of an ex...
If the cluster is anything like my oldsmobile was (which is probably the case) you'll probably remove that plastic cover, look at it, and then have it done in like 10 minutes. haha
How torn up is the headliner? Is it just the fabric, or is the entire board underneath toast as well? You can get some headliner material and glue it on, if you need a new board you can probably use the old one as a template and make a new one. Or maybe you can find one somewhere.
How bad are the seats? My guess is the padding is destroyed as well the fabric. You may be able to even repair that yourself, but I'm sure it won't be the same.
I think your best bet, cost wise, is to just get it all from another G6. Maybe check out salvage yards or craigslist for a totaled G6. If someone rear ended the hell out of a truck or something the interior could be in perfect shape.
Or you could go the newish route, ebay for instance is always good. You can check out GMPartsDirect
. You can get GM parts at warehouse prices, it can also provide some diagrams to show how things go together, problem is it doesn't really give any part numbers.