synchronize two webform select options
I do not need to synchronize, but combine (merge) them in one list. 
In Webform Views Select  I can also combine by using Rewrite Results, 

field "Item Number", exclude from display

field "Price List", 
Rewrite Result:
[value] - price [value_1]

Then I can get in a single select option list: 
20 - price 100
35 - price 200
40 - price 300