Considering that this group buy will likely be buying tooling for a company to use for future profitable endeavors, they should do absolutely anything requested of this group.
I don't believe it is any more unreasonable to think they can accommodate any request made of them than expecting us to buy moulding with no guarantee of return on investment to those that spend the extra money to make that happen... When you invest in a companies infrastructure or invest in tooling for a new product line for said company, you should get a written agreement of dividends on that product/service or a written agreement that your tooling will not be used for the companies gain outside of your orders.
In lieu of this, those that want ISO and are okay with paying for a company to open up a new product line should be willing to split that $8k (or whatever) expense between them and not among the entire group. Those same ISO customers are not offering anything to the benefit of the group other than more financial burden and the prospect of a bad business decision.
The very least that can be done here is offer flexibility in our requests as they will be making a profit either way. If they can't do it profitably, find someone else that can.