Phalaenopsis bellina is a species, so there are bound to be a few vendors with some available. They like to be REALLY warm, so if you can't provide that, hold off on getting one of those.
Hybrids can be short-lived in the sales channel. A good one comes along, so it is cloned, and lots of vendors carry them. Then a better one comes along and the prior one gets sold out and no longer easy to find commercially.
Sweet Memory is a fairly old hybrid - it was registered in 1982 - so is unlikely to be available unless you can find a grower with an extra he'd be willing to part with.
Mini Mark isn't particularly "new" either (1992), but is a popular mini, so some of the bigger-named vendors (Hausermann, maybe?) might have them.
How about another approach? Look at the online listings for
Carmela Orchids,
Big Leaf Orchids, and
Hausermann, to name a few. I'm sure you'll find some there that really "grab you".