Flat unfolded cards and traditional card blanks are great if you’re on a budget or don’t have huge amounts of information to include. Wallets are great for including lots of extra information inserts, RSVP cards as well as the main invitations themselves. There are also in_between options that give you the freedom of a wallet on the budget of a traditional card.
Letterpress: The designer and paper lover's dream, letterpress is visually lovely and highly coveted all over Pinterest. However, it is expensive because it is a fine art that requires some heavy machinery. Letterpress is the option to use when you want to support the artists making it, not because you think you should. Thomas Printers is a great option for people looking for letterpress invites on a reasonable budget. The other option to letterpress is to build your own, but you better have a serious love for the actual craft. The majority of your guests, sadly, won't know or won't care that your invites are letterpressed.