Actually I dun see how a folding knife can be useful underwater. Need to use it.. try to find in pocket.. and if u have not drop it and actually try to unfold it.. u'll have to hope its not suck in its folded position..
I use to buy stuff on ebay.. some cost a few K. While paypal offer certain protection, its not 100%.. I last bid for a marine part costing $800.. i never receive it and had problem contacting the seller. I filed a case with paypal and got my $ back (some exchange loss). I was lucky, but I can see things getting messy for other cases. Of coz, thru the years, I've successfully bought stuff totaling many thousands from ebay with only 2 unsuccessful transactions. One I got the $ back.. the other is still in US, shipping issue.. so have to pay and ship again and I dun quite bother.