For generate BrickLink Parts List[0] for created model using LeoCAD, in LeoCAD go to menu "File > Export > BrickLink..." and save its XML-file.

Then you could use this XML-file for order all needed pieces.[1]

[0] https://www.bricklink.com/help.asp?helpID=207

[1] http://guidetobricklink.com/uploading-a-parts-list

You can upload the parts list to Bricklink. They have a feature that attempts to find the cheapest combination of sellers to minimize cost.