Linnworks allows you to add either generic prices to your inventory items (Product Details > General tab), or also use channel-specific prices so you could use different ones on different channel listings (Product Details > Listing Descriptions).

Most channels also support the Price Change feature which works with channel-specific price entries and sends any changes you make to the prices to your channel automatically.

Please see here for full details and exceptional cases for the Price Change feature.

Details and instructions for adding channel-specific prices in bulk are available in this solution article.