Given the high value of your annual sales, and low number of items for sale, may I make two suggestions?
1. That you switch to a Business account.
2. That you then start using Flipwise, which is now available for eBay UK and whose cost is pro-rata based on your store size. It is integrated with eBay to help you prepare for tax-time by helping you keep track of every sale from start to finish [I am not affiliated].
Good luck with your accounting!