A simple and inexpensive way to change the appearance of an area is by changing materials on specific items. You can make new covers for pillows, seat covers or blankets to add a little Summer cheer. These may seem like very minimal changes but just these few simple items can make a big impact, especially in a smaller area.
For the Summer season you should look into golds, lively patterns and the usual list of bright and cheerful colors. A color making a notable appearance this year is coral. It is showing up in everything from clothing to bedding. Take a quick trip to your local mall and you will see what I mean.
If you like the idea of adding some Summer in to your area but bright colors or gold are not your thing, try looking in to organic fabrics, such as hemp. These can give a similar effect if used properly. You can create subtle or drastic change in your area, on just about any budget, depending upon the fabrics you choose for your project.