Questions about LM741 in an ECG Circuit Schematic
I strongly recommend splitting your gain between 2 or more stages, and not just use the IA for all your gain.  You will saturate because of offsets.

Now, that said, if you use an opamp with poor offset and bias characteristics, you'll need to high pass filter after each large gain stage, and this will add to your budget.

Other than that, there's nothing particularly wrong with the 741, so long as you leave enough headroom around the rails (pay attention to output ranges and common mode input ranges).

As for budget, is it safe to assume that you'll be building a lot of these?  Otherwise, I can't understand the difference of a few dollars, given all the time and effort going into the project.  Pennywise.....