Where are you based?
I regularly get my greetings cards designs printed. Just got my christmas cards back last week, and they’re selling nicely. If you use a local printer, with a decent quality digital set up, you’ll get them miles cheaper than these online places, but the minimum order is usually 100 of each design digitally printed
You’re also best selling them via shops. Card shops, newsagents, or I sell a lot in local bars. People won’t order cards offline. Why would you bother? Unless you’re Moonpig, or Funky Pigeon, you’ve no chance.
Drop me an email if you want to have a chat about it. Its a nice little earner if done properly
Oh… and you’ve left it too late really. if you’re only getting round to thinking about getting them printed at the end of November