Two quotes - difference of more than double? (pricey one doesn't even break cement)

I know, nobody wants to talk about money on here, but I'm really scratching my head on this one.

Need a rough in for a basement wet bar, which will be located directly next to current waste stack and supply lines. (First floor bathroom is directly above).

The first company I had out figured $1700 to run some PEX, break up the floor, and tie in the drain and vent.

The second company said they didn't need to break up the floor and that they'd just need to snap the stack above ground and attach a wye for the sink and run some PEX, but they wanted $3500.

They're both reputable companies.

You'd think that NOT breaking up the floor would cost less not more than double. I don't get it.

I'd suggest at least one more estimate. Often a contractor will not want a job but will submit a very high estimate figuring that if they do end up with the job, they'll have a very high profit.

Agreed, get a third quote. Do not volunteer any details about the technical approach, let the contractor propose what he thinks will work best for this situation.

Even without breaking the floor, which would be the correct way if it would work, they would still need a vent, and normally, that would involve enough time and materials, to do it correctly, that it would make the $1,700.00 one questionable.

HJ rightly points out the "on the other hand" to my point about over pricing a job. If one estimate is considerably lower than another, perhaps the low bidder is going to take shortcuts. In either case, another estimate is certainly in order. Say nothing about the first 2, but you might ask how the venting is going to be dealt with.