I have raised Shishitos and they don't weigh much. If you are wanting to supply 40 pounds a week for 8 to 10 weeks, 120 plants wouldn't even put a dent in that quantity. In my opinion, you would need 1000-1500 plants to produce that much. I am basing that off my biggest harvest of about 5 pounds, at one time, off of 30-40 plants grown in a high tunnel.

Price, get what you can get. I only charge 2 for 25 cents or 10 for a $1. I started putting them in pint baskets and people kept picking around in them, that is why I started the price per.

Most peppers I sell by the pound are $3 a pound.

Jay

$10/lb is too high for supplying to restaurants, IMO. I sell Padron peppers in 1/2 lb bags for $2.50 at market. I needed 500 plants last year to yield about 15 lbs a week. This was outdoors in zone 2 though, so they yielded less than they would in your zone.
I haven't grown Shishitos but I figure they are pretty similar to Padrons in size and yield.

In my Asian Market here, where there are a lot of Kreans and Chinese, SHISHITO is sold mostly around $5/lbs. In another fancier Asian market they were retailing it for over $10/lb.
That is where I got mine and got seeds from and am growing as Bckyardner(NO marketing).