Catalytic Converters on 2003 Mercedes-Benz ML320

I have a crack in 2 of the converters in my car. They are telling me it's 680$ per converter, plus labor?? Is that correct? Some places telling me they can replace and labor for 1300K? I need some help. I'm over my head on this one.

MB OEM part are quite expensive, but aftermarket "direct fit" replacements bolt in (no welding/cutting special tools) and can be had for ~$400-600 depending on brand and source. Muffler shops sell these for $1000 all day long significantly undercutting the OEM/Dealer expense. Any will work for 3-5yrs, arguably the OEM part is no more reliable/durable (it was subject to a recall for faulty welds).
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That sounds correct, and it sounds like a relatively good deal. I've seen these converters cost in the neighborhood of $1000 each, so it could be much worse.