Most tile at the box stores is ceramic, not porcelain. It's also subject to more variation both in squareness and in warpage. While you can find good quality tile at a box store, 2.50 a square is pushing it for quality.

Also, the labor portion will be more than the materials on this, so although the price difference between 2.50 and $5 seems huge, for a 300 square foot room, you're only talking $750 worth of difference. The labor will easily be more than that, so overall, it's not the tile that's the majority of the expense on a tile job.

I bought loads of $2/sf tile at Lowe's (their Rialto line) and it was through-body porcelain. No problems at all with it, and it looked great installed. I didn't run into any issues with warpage, and the size variation between tiles was minimal and within expectations for non-rectified tile. I've also bought subway ceramic tile, some decorative tile, etc. and again been very happy with all.

I wouldn't buy ceramic pixelated stuff, from a big box or otherwise. And just because the box stores carry that for $.99/sf doesn't mean they don't have decent stuff as well.

Thank you for your input.
I do not want to spend the money for porcelain tile. I'm going to put it in by bedrooms, so there is no chance of dropping things.

I really am trying to go as economical as I can. I'm getting ready to retire, and only have one more year of working, but have several projects left to do around the house. Replacing stained (from animals) carpet is one of those projects.

I got a ball park figure of $1200 for installation for the three bedrooms (and closets). (That is not a firm quote.) The tile looks like it is going to cost more than than.