wall decorating for rentals

I love walls- they feel like a huge canvas waiting to be filled. I like filling a room with color by painting and using accent walls. My last apartment, we got it before we actually moved in so we had time to paint. And literally every day I was there (about a year a half), I would exclaim "I just love these walls, they look so good against the flowers, the picture frames, the tablecloth, etc".

In this new apartment, all the walls are a cream white. This is really not my usual thing, because I love color but I am seeing the pluses to it. The light is really bounced off the walls well, and I see how it is possible to inject color into a room without necessarily painting it- like pictures, furniture, and fun accents. That being said, I still really want to decorate my walls. There are so many solutions for renters now- I will round them up for you. 

1. Fabric as wallpaper with using starch as glue

howaboutorange.blogspot.com

2. Washi tape or electric tape to make designs or patterns

charlesandhudson.com

molly-meg.blogspot.com

3. Removable wallpaper

lah-ti-do.blogspot.com

4. Decals

forum.homeone.com.au

These are different vendors I have discovered for the above options:
wallneedslove.com
swagpaper.com
designyourwall.com
wallpops.com
spoonflower.com
cutetape.com

Although these options are probably less expensive than wallpaper, they still aren't cheap (at least 100$ per room, and I'm not even covering all the space!). This is very hard for me because I can't afford to do anything with my walls now, but I am hoping to save up. 

The main things I would like to do is a black and white floral on an accent wall in the master bedroom, blue stripes in the baby's room, and a gold metallic pattern on the dining room ceiling. 

Does you have any other ideas for me?