Something I've noticed is that much of the wall decor available makes it's statement not so much through the "art" itself as through the frame and mat. Stores are filled with rather insignifcant items and hastily done splashes of color that make attractive wall decor because they have been framed and matted well.
Having an item custom-framed can be quite expensive, so the bargain-conscious will want to stick with off-the-rack frames. Luckily, hobby and discount stores carry pretty good frames and even mats in a variety of stock sizes and colors. (Though my first tip would be to invest in a good mat-cutter and learn to use it--will open the door to many more custom-looking projects.)
So what, exactly, should be placed in the discount frames and behind those all-important mats? That's where the real creativity comes in. I know of one designer who did an entire vignette of menus from her favorite restaurants in her breakfast room. The pages of a calendar could easily be turned into a set of botanical prints. I once saw a gorgeous set of framed buttons--one large, highly detailed button per frame, surrounded by a luxurious oversized double mat. In all of these cases, the "art" itself costs nothing or almost nothing. It's all about how they are presented. When it comes to budget art, there is often strength in numbers. One framed button might have been interesting, but a set of six made a real statement--the pieces took on greater importance.
Here are some budget art pieces I've done over the years:
Here, I simply converted some of my own photos to black and white and framed them in simple black frames. I cut the mats "gallery style" (proportioned such that the lower portion of the mat is exactly twice the height of the upper portion)
I gave these as a gift once, framing vintage postcards from the recipient's alma mater in the school's colors. The red silk mats were remnants I scored by asking the custom department to sell me their "leftovers."
I trimmed these greeting cards to fit into discount store frames. The "mat" in this case was the card itself, which opened to reveal the daVinci drawings. That the card openings were off center only made them more interesting to me.
I framed reproduction luggage stickers and ticket stubs from the Titanic once. I think a group of stubs or other reminders of a great vacation could make an excellent piece.
This pair was done by rubber stamping a design onto beautifully textured paper. No artistic skill required!
I put this together for my very first apartment. It's simply a framed page from an auction preview catalog. I haven't used it in years, but I may change out the frame and mat and give it a new home soon.