For your information, I have made some progress with integrating eBay and Erpnext.
The code is on Github here:
Currently, only the importing of customers and addresses really works well. This has been tested and is running now on our production server saving us a lot of time in entering customers and addresses on sales orders.
I am currently working on sales order import.
We spent a lot of time developing code to automate listing to eBay. But found this to be very involved with eBay categories and so on. Currently, we are using a temporary solution that output ITEM records to xml format to import to GarageSale (similar to TurboLister). The code is available for this if anyone is interested.
I guess I letting you know as some of you may find this of use.