As far as the $500 without approval, that's what our group does as well. It's called the President's Discretionary Fund, and has most definitely come in handy a few times when we needed to pay for things quickly between meetings.
When it comes to voting, another option that we utilize to "narrow things down" before bringing them to the floor is a budget committee. In your situation, our budget committee would have analyzed each request individually to determine which ones met our criteria for what we can pay for, and which ones we are able to afford. Then we would have taken the ones that met the criteria, prioritized them and brought each one to a vote individually without regard to the others. The big difference is that rather than being submitted as a wish list, we would have required each teacher to submit a budget request with information on what they were asking for, including details regarding where they planned to purchase it, and if they had investigated cheaper alternatives. Budget committee deliberations are confidential to avoid hurt feelings, and priority is given to requests that affect the most students (ex. something that helps the entire student body is given preference over something that only benefits one classroom).
You didn't mention the nature of the requests that were being made, but if they are relatively small amounts, your group might want to consider teacher stipends. We use these, which has definitely lowered the number of budget requests we receive for small items. Just be sure to require receipts.
Do you current by-laws reference any particular source?
The leading parliamentary reference is Robert's Rules of Order. I suggest that you pick up a copy of their 10th edition and read up on the various aspects of voting procedure. Then, you can confidently debate how the by-laws ought to read on this matter.
With regard to the expenditure issue, $500 without approval does seem rather high, but may not be depending on your typical annual budget.
We do have bylaws that have currently been changed by this president that I have been frustrated with. There are two sections that she referenced the voting rights to our entire group rather than the board.
ARTICLE IV - MEETINGS
Section 5. Voting Rights
Voting rights shall be reserved for members of the Association.
ARTICLE VI - MANNER OF OPERATION
Section 4. The executive board shall be empowered to spend up to $500.00 on non-budgeted items. Any expenditure over this amount shall be approved by the general membership.
I wasn't sure if these have to be passed this way or not. Like I said, I have never been on a board before but I would assume that we are there to make these decissions for the entire group.
While not even the same group of members are going to agree completely on any given issue, there does need to be consistency on who votes so that they aren't doing so "in a vacuum" (i.e with little to no reference and/or historical information to guide them). Usually, PTO/PTA's or equivalents (such as your association) reserve most voting issues to the board members. General membership voting, which is what your group does, is different "animal" altogether and is conducted in a tightly controlled, specific manner.
Does your association have by-laws? If not, I suggest that you volunteer to head a committee to form by-laws? If your association already has by-laws, I suggest that you offer to dust them off and help interpret them for the board members with respect to voting procedures, especially.
Our Catholic School has a Home and School Association. We pay no dues and are not part of the national PTA. This is my first year on the board and I have not been happy. The way the board meetings as well as the general meetings are run by the president are outrageous. For example, this year the teachers had a wish list of about 15 - 20 different things that they would like to use some money from Home and School for. Instead of the board narrowing this list down to 2 - 3 items, the president felt it was necessary that we have the general group (20-35 people, not always the same at each meeting), take a vote on how to spend the money. You are never going to get everyone to agree. I believe that this is the responsibility of a board.
