I can recommend NOT going with Walmart Bell brand tubes. They are fine in a pinch, but I've gone through 2 tubes in a day from them and still had to walk home.
I got to work in the morning just fine and came back to the bike rack in the afternoon to a flat rear tire (why is it always the rear one?!). I take out the tube and it is split up the inside of the tube. I can find no cause for it (I have an old tube as a tire liner).
So, I go through the trouble of putting in a new tube, and take it to the mechanic to air up after I make sure things are where they should be with my frame pump. He carefully airs it to 60PSI for me (range is 55-75). I get on the bike path going home and all of a sudden BAM! like a gunshot went off and I felt air whooshing past my legs escaping from my tire. This tube split along the inside again, in a different spot.
Neither tube was patch-able, being a long slit in the tube (or at least not the kind of repair I'm willing to attempt!). The first tube had been patched along that inner seam and it seems like the slice might have been from underneath the patch or at least close to it. I could find no puncture culprit in any of the cases- not even the first tube's patch-able hole.
When I got home I went over the tire yet again looking for something irritating or sharp. Rim tape is fine, nothing in there, nothing on the old tube liner. Put in a tube sent to me by Schwinn with a back wheel they've given me under warranty. No problems. Brand was Sunlite? maybe. Yellow box.
As soon as we get some money I'm going to talk to the bike shop here (we just moved here, my husband got me a map from them) and replace this other cheap tube on my front wheel before it causes trouble too.