The original poster is asking about Cessna seat rail attachments. Sadly I included my set in the sale of my last Cessna otherwise I would loan them. Surely there is someone on this site who could lend some to rioncentu. Unless he owns the said C210, $400.00 is a bit much to tie down camping gear in someone else's aeroplane on a one off trip. Sadly there is no really good alternative.
If however, the OP owns the said C210, $400.00 is money very well spent.