Mercari Bundled Shipping: what is the best way to insure expensive bundles?

[Leopard_Print_Unicorn]

I have started a serious downsizing of my collection on Mercari, since my husband already had sales set up there and it’s fairly straightforward and easy to deal with. Mercari shipping options only insure up to $200, so I was careful to only list ponies up to that value. However, Mercari automatically let a buyer purchase and check out with a bundle with combined shipping for a total value of $400. We went ahead and shipped the ponies but I was very anxious until the sale cleared last night.

I can see that there is at least one more seller letting go of some rare ponies over $200 that are currently listed with just the Mercari $4.99 shipping. Is this common practice? For now I have added a disclaimer: “See my other MLP listings. Mercari shipping insures up to $200. For bundles over $200, please message me first for total with insured shipping. I will hold the items for you. For buyer and seller protection, I reserve the right to cancel bundle sales over $200, but will hold items for you to repurchase with insured shipping.” And then getting an insured shipping option and giving the buyer the option of combined, insured shipping vs buying each item separately covered by Mercari shipping, whichever is more economical. I looked and I don't think it runs afoul of their TOS. Has anyone found a better way to cover this kind of situation?

In general, we have found that items less than 1lb are cheaper through USPS, and more than 1lb but less than 5lb are cheaper through UPS. I have not encountered a situation yet when we have sold a bundle more than 5lb. For rare, high dollar ponies, what is the consensus on the best form of shipping with added insurance to cover the sales value? How do we go about selling that through Mercari? Once I build my reputation as a seller, I was thinking of doing some of my valuable ponies, like some G1 rares and Nirvanas, and my G3 Beach Belle and Caribbean Delight set, off Mercari and directly on the Arena for this exact situation, so that I can communicate with the buyer every step of the way and agree on appropriate shipping to cover the value. But I’ll admit I did not think ahead of the scenario when a Mercari buyer made a bundle for above the insured value.