I saw someone comment once that they use a free/cheap service to actually file their taxes (I think it was FreeTaxUSA) but they go through the process on TurboTax to compare numbers. It's a little more work but I thought it was a good tactic since as I recall turbo tax only charges to file-- it's free to use and go through their checks and instructions.

I switched to FreeTaxUSA last year and found it to be perfectly adequate, but if I were less sure about it, I think it's totally worth the savings to find out what turbo tax thinks and then file elsewhere.