If you delete the product, the logs get removed as well. I will suggest making a generic "website" product and either set the price to 0.00, so the buyer can enter her own price or you can edit the price each time you are selling a new website. However that approach will
work if you are only selling one website at a time.
I see now that you have multiple websites on sale. If you want to get a little tricky, you can still create a generic website product with base price of say $1 and for each website you are selling, append the following to the purchase url:
&on0=Website+Name&os0=[put_actual_website_name_here]&amount=[cost_of_website
- base_price_you_set]