Actually I was hopping for one in 2 hours 31 minutes and 1 second (lighten up)
I only mentioned time as an issue, since you can back after less than 3 hours expecting to have gotten a reply.
1. Portable, handheld
Still kind of vague. Do you need an NDA before revealing more details? Understandable if you do.
2. The amount of data is minimal, just detecting similar code within similar devices (to begin with at least)
Code? I'm not sure that is possible. Perhaps you meant something other than source code.
3. 30-60 meters
So, XBees would work well.
4. 3-5 devices would be communicating simultaneously
With each other, or with a base station only? This might require series 2/2.5 modules.
5. Depending on the parts needed, but the prototypes should be less than $1000 (which I think is much, but open to discussing)
Wow, someone with money (or reasonable understanding of costs, at least). An Arduino with XBee shield and XBee should run about $75, so your price allows for a very fancy box. Unless there are expensive sensors involved...
I'm not local to you, or I would be interested.