Non-QM Pricing model

Currently sit on a mortgage originator trading desk with primarily a GSE product background. We have recently pivoted to being a heavier NonQM shop who shows the loans out via bulk whole loans. In a effort to better gauge the market I've been asked to build a estimated securitization take out price. Not sure where to start on something like this. Are there any generic excel models out there that cover something like this? We looked into Index but it is just too cost prohibitive. Open to any suggestion on where to start.