What i understood from your requirement is "since the product information is the same, you don't want to renter the information in second site". Since both sites are x-cart based Or similar system, you can simply export it in CSV and edit the price and import it. This is manual.
The automated solution is "Write a script that exports the products data from site 1 and import it into Site 2 automatically except the price data". In Site 2, if you have price already defined, don't overwrite it. If the data is empty, you can define it.
If need any help further, drop an email to
sales@mercuryminds.com.