The size and format of your invitation can help to enhance it's style but it's also needed for quoting too. Here I have laid out some examples to help you find what might be right for you.
Most couples I work with tend to go for an trifold invitation as it's a very practical design - there are no loose sheets that could get lost but it includes everything you will need, including a cut-off RSVP. All budget invitations are printed onto loose A5 sheets but you could change the format to one you prefer more and turn it into a semi-bespoke design.
The most expensive options are those that are the most complicated: gatefolds, pocketfolds and square folded designs. The cheapest ones are the easiest to print: loose sheets or sheets with folds.
The average invitation is two or three pages, which would invite your main invitation page, a page of more information and a wedding map and/or an RSVP postcard.
You may want to think a little more out-of-the-box. Why not print onto fabric, a tea towel for instance?
If you want to chat to me in more details feel free to get in touch.