Bump... GY I haven't seen you post in a while but if you're still thinking about doing this here are my ideas:
Here's what I think would be the best way to approach this issue.
People won't pay money if they don't know exactly what it's being used for. So what we do is we make a thread that says:
1. Here is a specific product I'd like to test (just one product- say EQL testosterone enanthate 10 ml).
2. Here's how much it will cost to run the tests.
3. If you are sure you can donate to this specific test, post here.
Then, if enough interest is generated and enough people promise to help contribute to definitely pay for the one specific test, then you can set up some method of payment.
I think this idea is better than just a general body of people paying money for a whole bunch of tests. For example, I personally don't care if something like Supra labs gets tested because I will never use it. This way may be a little harder to organize because you don't send products to be tested 1 at a time, but you could create several different threads like the one I mentioned to determine which ones will be paid for and by whom.