From what I've seen
ModchipWorld has the best prices on Qoob Pros
The Console Corner has the best prices on Qoob SXx
and Divineo has the best prices on ViperGCs
I wouldn't even bother with a special case for fullsized media...
the best quality media for the GC is the Ritek/Ri-Data G04 Mini's... http://www.meritline.com/ritek-mini-dvd-r-media-4x.html
I've used them exclusively and I've NEVER once had a game not boot and I've never once had to tweak the GC's pot. Also I've modded about 6 GCs now and had the same results on all of them with that media.
Of course it also depends on how good your burner is, I recommend one of the NEC drives.
You'd be better off spending money on a new drive then on a replacement case. so A. Spend $$ on a replacement case, burn to full size media with a crappy burner. Have low compatibility, burn multiple times, have headaches with Pot Tweaking, No compatibility with other GC consoles that don't have replacement cases or tweaked pots
B. Buy a good burner, use the proper sized and quality media, no pot tweaking, high compatibility, you can use your backups on any GC with an softmod. AND now you'll get better compatibility with your backups for other consoles as well.
a new burner will only set you back about the cost of a replacement case.http://www.newegg.com/Product/ProductList....Submit=Property
Use one of the NEC (3520 or 3540) burners with Ritek G04 Mini DVDs and your burn success rate will go through the roof.