I confirmed that injection molding is totally out of the question (well, based on the casters I spoke to). One said it would be between $3,000 and $8,000 for the mold itself. The mold would be made of aluminum or steel, created by robotic machines based on the specs in the CAD, and then would be altered to allow plastic to flow in and for the buttons to be ejected out. Then, it would cost between $200 and $500 to even put the mold into the machine. At which point, they'd push the GO button for like 5 seconds before hitting STOP, because that's all the time it needs to make 300 sets. So, it'd do a quality job, but only if we needed 300,000 sets.

Based on the lower of the mold costs injection molding would be doable. Risky, yes. But doable:

Mold $3000.
5 colours setup: 5 x $200 = $1000
Plastic is cheap. Let's assume $500 ($100 per colour) gets us more plastic then we could ever sell.

Now if that gets 300 sets of 5 colours, you'd need to sell 100 sets at $45 to break even. Let's add $5 for sundry costs... $50 for a five colour set anyone? I'm confident that you would sell 100 sets at that price. Anything over 100 sets becomes profit (which might be another hassle to deal with...how to distribute...)

Of course that does require getting the mold at the $3k figure. For the $8k figure you're looking at selling 200 sets to break even which is significantly more risky, (Possibly too risky)

Don't completely rule out IJ yet. The lower numbers aren't looking that scary.