Looking for a lower receiver

Hey everyone, i've been cruising the forums here for a while looking for good deals on airsoft guns. but now i have a few questions. I tripped and fell on top of my KWA M4 :/ i cracked the lower receiver next to the buffer tube.
I was wondering if anyone had a lower receiver for sale. I was also wondering if the 2gx gear box will fit in a different brand lower, and if a plastic lower will do the job.

Thanks in advance for the info. cant wait to finally get out to modern warzone, my cousin just joined bad company so i think i will be going out there soon.

I got one just bring It by my house and see if we can fix it. See you soon. Tell bear to give you my number.