Where can I source...

[SunsetRunner]

A product box, manuals and the straps that should have came with my device?

I bought it second hand, and only received the device itself, the strap that was on it and the charger.

Ive seen a few empty boxes on ebay but its literally just the box, no booklets etc.

All through my life I've always kept all boxes, booklets and accessories for any item I've bought such as phones, tablets, laptops etc.

[Odyssey13]

Hello @SunsetRunner ! You sound like me. Always like to have and keep the boxes, manuals and receipts for my purchases. There wouldn't be a way to get an empty box other than getting one from eBay, but do you really need it? There is no manual in the box, only a paper with the address of the Fitbit.com website. You can download and print the entire manual, but there are a lot of pages in them. Sorry there isn't an easy answer to your question. Did you ask the seller if they had any of the items you wanted? 

[SunsetRunner]

Ahh OK then, thank you for your reply!

No I didn't think to ask the seller.

I have the fitbit versa special edition lavender but only got one of each strap in the small size, not the halves in the large size and as far as I know, other than an empty box off ebay, I can't buy any official fitbit accessories separately.

[Odyssey13]

Here is the link to the Versa user manual and related articles - click to go there

Fortunately for you, the Versa family bands can be used on any of the Versa devices. You can buy bands and a charging unit that would be the authentic Fitbit brand. So, while you can't have it all, you can have pretty much. Whatever you do, keep on stepping!

[Odyssey13]

Link to Fitbit Store online - click

Check for sales, it's getting closer to the holidays!