Abs don't cost money: Return that sh*t you bought from that television commercial that aired at 3:00 in the morning. To train abs, you do not need one of those roller things or special contraptions. The products on television are good, but only to a certain point meaning that there is little room for added resistance. All you need is a mat and something to hang from to get great chiseled abs.
Body Fat: Everyone has abs, some people don't see them because there is a layer of fat around your waist. On the days you are not lifting, try some cardio and look into some thermogenics.
It's quality, not quantity that counts
For lower abs try leg lifts (many variations of this exercise -- be creative
) And/or lay flat on your back, lift your legs straight up as if you were going to touch the ceiling (body should look like an L) bring them back down, and back up in a continuous motion. do not lift your shoulders off the bench.
Add some oblique exercises in between.
Now for upper abs, i don't like the fact you can go over 8 reps. So i do weighted overhead pull down crunches. But ill do some regular crunches once in a while (declined bench)
Focus and concentrate.
Best thing you can do is get a gym membership. Or if your packed on time, a sturdy declined bench with foot straps (added weights), hang a pull-up bar a do some leg lifts, pullups...etc. Theres many variations without spending lots or any money.