Don't get me wrong: I'm definitely pro-money for GT services! And more is better! But I don't like the notion that we have to choose between one end of the curve or the other, nor do I agree with the (too-common) notion that if there's no money, there's nothing that can be done for GT kids.
How about grouping the GT students within a classroom? It costs no extra money, assuming there are enough students to fill a class--it uses the same number of teachers, classrooms, etc. as not grouping them--but it allows at least some course compacting or acceleration. Even if there are different LOGs in a room, differentiation is easier if you don't have the full spectrum of the Bell Curve all in one place.
How about assigning projects that allow GT kids to go further, do more? Research projects or advanced math work are good opportunities for this. Allow GT kids to spend less time on things they can already do (this is big!), and let them devote that time to their project instead. No extra money required, just a redistribution of the child's time.
Allowing more independent work is often helpful. I think GT kids need a teacher, and they should get their fair share of the teacher's time. GT doesn't mean "able to learn everything on his/her own." But if given a choice between sticking with the class and having the chance to progress independently, many kids and their parents would vote for the independent work. This may not work well for extroverts, of course.
I'm not a huge fan of differentiation as a policy choice. I think it's too little and too easily undermined. It's also the one GT service that can actually wind up harming a GT child, since if a child gets good differentiation one year and zero differentiation the next, it is the same as holding back a child a year or more! Not what a GT kid needs!
But with that caveat, if there's nothing else available and money is an issue, dedicated teachers in a school that really cares about meeting the needs of GT kids can make differentiation work, often with little time or effort and no money. Sometimes even using the same materials that the rest of the class gets and just issuing different directions about the assignments.
This is just an off the top of my (not-an-expert) head. I'm sure there are plenty of other things that can be done that are not expensive.
