To access your price level mappings, go to Setup > Customization > Record Types > SFDC Price Level Mapping > List (or View Records).
To map a new NetSuite price level to a new Salesforce price book, first create the new price level in NetSuite and the price book in Salesforce. Then, in NetSuite, go to Setup > Customization > Record Types > SFDC Price Level Mapping > List (or View Records) and click the New button at the bottom right to add a new mapping.
To see your NetSuite price levels and their respective internal IDs, go to Setup > Accounting > Accounting Lists. Make sure the Type field at the bottom of the page is set to Price Level. If the Internal ID column is not displayed, go to Home > Set Preferences to set the preference to display internal IDs.
To see your Salesforce price books and their IDs, use the Salesforce data loader to extract this data. Please check the Salesforce user guides for info on accessing the data loader tool.
When mapping new entries or changing existing ones, please be sure to refresh integration caches when you are finished.