Hi, explorer232, greetings from Czech Republic!!!

As we talked here before, I'm definitely interested.
I made a little simple investigation about return of invested capital and avalon looks good for now. (Real parameters will be different, but for imagine and comparison it's enough.)

I have to say I don't know details of your design, but there is possibility of overclocking, as described in datasheet of avalon chip. (And discussed in other avalon-clone threads like this).
Did you think about possibility of supply voltage/clk frequency tweaking?

And second note, please think about 28(-35)GHs variant, I mean 10 avalon  modules shield. You always can use 3 modules only, but benefits of modularity are known ;-)

If I can provide you any help, feel free to ask.

Ramirez