As someone who has shipped a lot of stuff over the years, can I give a small perspective from the other side? I want to preface this by saying, while I also think 30$ is a bit dear, I don't think it is necessarily completely outrageous either.
Who you ship with, and where you're shipping to, will affect shipping price. If you're shipping from the bottom of California to the top of Maine the package has to cover a lot more distance and most carrier's pricing models account for that. Furthermore these things typically go airmail, where packages which are oversized and delicate (like barrel liners) are again more expensive. On top of that, if you're not near a hub, delivery can also be more expensive. All of this really depends on the carrier and your integration with them. If you ship USPS, it'll tend to be cheaper than UPS, which in turn will tend to be cheaper than FedEx. These are all major generalizations, of course. But which carrier a given vendor chooses can significantly affect price. Confounding that is how a webstore's shipping calculator works. Nobody is going and manually figuring out how to stack all the parts in your order into a perfect jigsaw puzzle, sourcing the ideal box, and then fetching you just the perfect quote. Typically they're based on weight and weight alone, and then fetch a real time price from the carrier. For something like a barrel liner which is light but bulky, you often see companies add a high shipping weight in order to get their native shipping calculators to spit out a vaguely correct price. Depending on the margins on a given product, you may price that to aim for the middle of the market in terms of shipping costs, or the top so you never lose money, or the bottom where you don't care if you lose a little money. The latter is often seen on MAP priced products, which many of FX's products are, because retailers can't differentiate themselves with advertised price alone.
And there is one final thing. Lets say you are going to ship with USPS, generally the least expensive, and you're going with Mr. BigTinBoat's price of 20$ for the package. What about insurance? Depending on which insurance you purchase, there are multiple shipping integrations that offer third party insurance or carrier insurance which tends to be the most expensive, that could be anywhere form less than 2$ to ~10$. And it does make sense to insure it. I've had all kinds of insane package destructions over the years, including one time UPS managed to put a 45 degree bend in a cold hammer forged steel rifle barrel. I don't even know how they physically managed it. So believe me, whatever it is, they're more than capable of destroying it or simply losing it. And if that item is lost or damaged, believe me the customer isn't going to give a rip, it is on you the vendor to make sure they are made whole.
So can I see how a vendor could get to 30$ on shipping a 700mm barrel liner CONUS? Absolutely. Would I personally go with one who charged less? Yup, probably. Is the higher shipping price perhaps part of the reason why this vendor still has the barrel you want stocked while everyone else is sold out? Maybe something to consider.
Just my 2c. I hope it provides at least a chuckle if not a little insight into what might be the other side of this potential transaction.
