Hello @Wysteria_Norn!
I think it is super exciting that you want to make your own tarot deck- what a cool craft! 
Making your own deck is no doubt a lot of work, but as a result you’ll have a deck purely and uniquely your own 
I’ve used printing companies for things like custom calendars, but I’ve never made my own deck before. The Free Printable Tarot on Spells8 suggests the following:
You may print them on Photo Quality printer paper and maybe even laminate them so they’ll last longer!
From Spells8: Free Printable Tarot Cards
I’ve also some people choose to use multiple sheets on regular paper- you can get your ideal card thickness by stacking sheets on top of one another.
That reminds me that @MeganB was brainstorming ideas for making her own oracle deck- perhaps she has some advice for you about printing methods?
Wishing you all the best, Wysteria- have fun with crafting your very own tarot deck! 
