I believe pool filter sand is relatively cheap if you could get your hands on some and looks better than the play sand IMO. I avoided the play sand after seeing the color, just knew I wouldn't be happy with the way it looks.
If you're looking for some cheaper hardier fish clownfish aren't expensive, for the standard Ocellaris, and they are pretty peaceful when it comes to clownfish. Chromis are another, the green I believe isn't expensive, and they can be kept in some sort of group but I can't remember the specifics there (odd/even numbers or that sort of thing). I believe there are some cardinals that aren't too expensive that will school also so you'd be able to have a few. Those I listed will do well in a community style tank. The only ones mentioned I have experience with are the clowns though, I have read some about the other just not as much as if I were adding them to my tank. I can't think of any other cheaper fish at the moment that would do well together....
I'd find one particular fish that you know you want, even if it is to be added down the road, and be able to plan your stocking that way, adding the more peaceful and hardier fish first until your comfortable.
I can't even remember now what size tank this is to suggest much of anything else. I know there had been a couple fish I had looked into that would do well in groups but they were more expensive and harder to keep, reasons I've shied away from them.
I also really like the different gobys and blennys, I have one blenny. Most of them aren't very expensive.
Oh, love my toby puffer too of course!
If you're concerned about cost at all, stay with FW.