Be very careful of Ebay GSP, they will take your item and dispose of it, if they decide they won't ship it. No other line of action is possible.
Purchased a set of EsCos fuel lines on ebay that shipped via GSP, ebay took them, issued a refund and gave no explanation.
The seller and I went to considerable effort to get them back or have them shipped by an alternative method, but we got nowhere.
It was a desktop decision by ebay and/or pitney bowes, as they never looked at the item. They blamed each other rather than manage the issue. They contravened there own written guidelines and just stopped responding when that was pointed out.
A bunch of thieving lawless cowboys.
I've heard of that happen with large items, although it was never made clear who ended up at a loss though. I was once tempted to buy an engine block where ebay listed it as $200 shipping, which was mental cheap. But I didn't want to risk it for both my own money and what impact it might have had on the seller, as knew it was unrealistic for it to be shipped that cheap.
Clearly if the item is an odd shape/size, perhaps very fragile, considered dangerous goods....which any mention of "fuel" could imply, you're taking a risk