[T. O'Heir]

"...buying a holster that fits my needs..." Don't be daft. Make your own and it'll be exactly what you want. Cost you far less too. Buying a holster. Geezuz. snicker.
"...no retention device..." Would very likely cause a commercial maker to have a stroke over liability fears. Kind of doubt you'll find a plastic holster without something.
Been making my own leather holsters for eons. No straps or any other mechanical retention devices other than wet forming. Works like hot dam.