[gavinray]

Hard to find more protein per dollar than $2/lb of canned chicken with an equal or even similar Protein Digestibility-Corrected Amino Acid Score (PDCAAS).

[littlexsparkee]

If my numbers are right, you could undercut that slightly with combo of pulses/tofu/rice, albeit with higher calories/carbs depending on mix.

edit: seeing the same as lantry, that eggs or milk are cheaper animal source

[lantry]

eggs and milk are generally cheaper per gram of protein, and both have the same PDCAAS as chicken