you can order the fan/motor assembly from an appliance store..the question would be whether the model hood you have, accepts the current fan/motor assemblies.

figure out the model number of the hood you have, and ask a viking dealer in your area which fan fits it.

then you can shop around for a good price (internet).

Hood & backsplash w/ shelf for $400? Very good price! I wouldn't be surprised if the new cost for just the backsplash & shelf is in excess of $400.
The mechanical/ electrical components shouldn't be any real problem. Here's one option:

Here is a link that might be useful: Fantech

Thanks! It seemed like a good price especially after I found some pricing for the backsplash alone above $700. Seems like it won't be that difficult to get the fan. It's the basic wall mount professional model. Thanks again for the responses.

im also looking at buying a viking hood -

VCWH4248SS

http://www.ajmadison.com/cgi-bin/ajmadison/VCWH4248SS.html

However, I would rather NOT pay a premium to use the Viking external 1200 CFM blower, when I can just buy 1 from Fantech for 1/3 the price ($400 vs $1200). However, AJ Madison (and ever Viking dealer) is telling me i MUST use a viking only blower.

Can I disregard that upsell and just install a Fantech FKD 10XL and use 10" duct ?

I'm guessing its a warranty only issue on using another maker's blower - i.e. that will be the first thing blamed if, say the light bulb socket breaks or a switch dies and they will refuse to fix it under warranty...