It's not so much that the part is hard to find, rather, I'm guessing that most of the people you've talked to (India/consumer sales/consumer tech support) lack the knowledge/training or whatever to find what you're needing.
I'm out "sick" for the next 2 days (returning to work on Wed 12/23/09), else I could post the part number now.. So unless you've found what you need already, or want to use what I'm saying here, then just wait till then and I'll post it if it exists as a separate component.
I don't know wether or not you got a chance to see the parts list I'd posted several days ago.. I did one for each model of system talked about on this forum.
The motherboard part numbers for the Mini10's that have daughterboards (yes, some don't) are as follows: 5RXKK, 8TPN5, C971R, C973R, VVRDP
These are (at Dell) referred to as PRIMARY part numbers. Unless their application doesn't allow it, though I can't think of a good reason why it wouldn't.. All they would have needed to have done is find out which motherboard it is you've got.. then to open the BOM utility on the left side of this web-app, put in the Primary part number, and *IF* it is actually available as a separate part.. then it would show up as a COMPONENT part off of the Primary. Then its just a matter of looking that component part up on IDD and producing a quote..
Whole thing should take only a few minutes to do.. You can give them another shot, or just wait till Wed and (it should be rather slow that day), I'll post up what I find, &/or make you a quote if you need it.