Despite the fact that your guests should and probably do feel honored to be a part of your wonderful day, it is only appropriate that you give them favors as a token for their attendance, any gifts they have given you and especially if they have traveled or rearranged their schedule to attend. However, that is not an indication which requires spending a great amount of money nor be typical or easily anticipated.
One inexpensive way to kill two birds with one stone is to use small and economical containers, each filled with different sorts of succulents. On the front, you can put labels with the name of each guest and simply the number of their table at the reception. Therefore, not only does it keep you from making seating assignment cards but is a token of your appreciation which can grow and is long-lasting.
Select something meaningful and useful to which you can attach a card letting each guest know that you have made a donation to a charity on their behalf. No matter the organization, each attendant would be both surprised and humbled by the thought behind your decision to do so.
Find something local and unique to your area, whether candy, granola, tea etc. and package them in modest containers. If you wanted to extend yourself, cover the containers with local maps giving extra meaning to guests who have traveled for the occasion. If you choose not to use a map as a cover, simply fold it into a uniquely styled tag with a hand written message.
Any favor would be appreciated but there are many ways you can show your gratitude while both remaining in your budget and thinking outside the box.