My little bros in the exact same boat, the APS is pretty cheap for a full metal m4. The problem is APS's gearbox is not great by any standards.
I have a Dboy AK74 that is brand new I would be willing to let go for around $125 if you're interested.
Other than that my suggestion would be to save a bit more and go for a JG. They are the best bang for buck on the market in my opinion, the gearbox is strong and it is a great platform to perform later upgrades on.