Note: The BiggerPockets Calculators do not offer me what a goodl ol' fashion Excel spreadsheet might.

Rates are usually in the high 8s or low 9s, and you are likely going to pay 3-4 points for these loans. 

BiggerPockets also has a calculator to analyze deals, and I highly recommend you start this as soon as possible, even if you are not ready to buy.

Rents may be high, but where are taxes and insurance.

The last thing you want is to have a home run deal that theoretically should be a high-profit flip but is ruined because your contractor screws you over in some form or fashion (late deadlines, inaccurate scope of work, etc.). 

The offering would be at 490 units at $1000 unit

Seems like everyone wants to wholesale here - The competition is really high - I dont really wholesale unless it makes sense for everyone but my advice would be to try and hit the lists that arent already super flooded ( pre foreclosure, vacant, etc.) 

I'm more focused on residential properties, however, I offer a bit of everything.

Or does one product typically offer better rates?

The market is at historic highs and could break at any moment.