Re: looking for a rack mount mixer
That looks like a really nice little 1RU mixer! But, what else would you expect from APB?
For your amplifiers, you may want to consider (these fit well within your price range):
http://aa.peavey.com/products/index.cfm/item/117721/ - for the larger size... rated for 150 watts, and has a module bay.
http://aa.peavey.com/products/index.cfm/item/117720/ - for the smaller size... rated for 75 watts, and has a module bay.
Then, you can use one of these for the tone generator:
http://www.toaelectronics.com/mod0003.asp#S-04
...yes, it plugs right into the back of the Architectural Acoustics amplifier's module slot. The Toa 900 series modules and the A/A modules are interchangeable.
Of course you could also use one of Toa's own mono amplifiers to get the job done, but they are not nearly as flexible and useful as the Architectural Acoustics amplifiers are. Though these seem to cost a bit more than you are willing to spend.
http://www.toaelectronics.com/amp0002.asp
So anyway, there are a couple of solutions to your question. Honestly, with the A/A amplifiers, you would be well served to just buy the larger size amps for all if you can't get the smaller size ones. Having the extra headroom never hurts and standardizing your models can be useful. The price difference is very minimal. Personally, I'd go with the A/A amplifiers because of the price. They perform extremely well and have some great options for the 70V system, including the option slot where you can stick the Toa module.
Have fun and good luck out there!