So keep the large canvases at the Gallery until you have built a fan base, BUT there are some possibilities that may be unknown to you.
Make Artist Trading cards - Trading Card Sized works of original art, there is a market for these products, they are easy to mail, can re scanned true to size and you can quickly create a fanbase of artists interested in your works.
You can expect between $3.00 - $100.00 for your ATC's..as people start to look for your works they become interested in buying larger works.
They are a fantastic way to get your work out there, its almost as if people are paying you for a business card!
Here's one artists description of how to make your very own Artist Trading Cards
There are no rules other than that you should stick to the 3.5' x 2.5' format like a sports trading card, any medium will do.
Here are some example on eBay, many people also sell the blanks -canvases/watercolor paper etc., already cut to size.
Read How to make the Cards yourself
How to Make Artist Trading Cards
To be quite correct: ATC's or Artist Trading cards are intended for trade between artists, of course this isnt stopping anyone, if you intend to sell them they would be officially called ACEO's (Art Card Editions and Originals) as explained by the artist below
Getting Started With ATC's