Lowest price- Spot Prawns
For cook at home:
99 Ranch has the big ones for around $17.99 a pound
Arcadia Supermarket and HK Supermarket also had them for around the same price.
A month or so ago, I went to New Capital Seafood, and they were having a special at $1 a pound (of course, they only give you about 1/2 to 3/4 pound for $1). There was a limit on how much you could order depending on how big your party was.
Full House in Arcadia generally sells them for around $20 a pound.