Personally, I neither have nor use the “usual” straitjackets. But for those who think otherwise,and for those who admire the idea of being locked in clothes I found a couple of links.
Heetkamp (Dutch company) manufactures various kinds of human restraints. Nothing naughty or fetishy – they are supposed to be used in the “professional” environments like hospitals, clinics or jails. Click on “Artikelen” (Products) to see the photos and description (Dutch) and “Prijzen” to see the price. The photos are quite self-explanatory, but if you are stuck, go to any on-line translators like FreeTranslation.
For example, this lockable “catsuit” (Artikelen -> Hansoppen ) can be customly made (sewn in sleeves, closed sleeves, legs with feet, non-breakable fabric, different colours)
Their line of cuffs, collars and magnet locks is very impressive
And this is how you can lock yourself into one of those straitjackets with magnet locks (German).