Miz Mooz is OK, better than some shoes available out there and certainly better quality than most of the other lines on QVC. I don't own any - I bought and immediately returned the Miz Mooz Fawn boot a few months ago from Zappos because I was looking for a less expensive "fix" for my AS98 addiction. I couldn't abide the cheap synthetic tricot lining.
The style vibe is very similar between the two brands and often Miz Mooz merely repeats an AS98 style a few seasons later at a slightly ower quality level. AS98 shoes and boots have leather linings and fully stitched sole construction. Miz Mooz shoes and boots are mostly glued together and while some of the Miz Mooz sandals have leather linings, most of the boots and shoes have synthetic linings. You'l pay about twice as much for AS98 product at the beginning of the season as you would for a similar style Miz Mooz. I wait until closer to the middle or end of a season and buy AS98 at that time. It is worth every penny.
I don't know the exact relationship, but Miz Mooz and AS98 seem to be affiiated in some way. You can buy both brands at Infinity Shoes, onine and at a boutique in NYC. AS98 also has a dedicated website, but shipments from the AS98 are shipped from the same address as Infinity.
And whether you buy from Infinity or direct from AS98, you can split payments over three months using their credit card payment processing service.