With regards to your post about upgrades: I own an ICS M4 and have put well over $1000 worth of upgrades into it so from experience, I would suggest not changing the nozzle because it will more than likely cause feeding issues. Stick with the stock ICS one.
For mags, the king arms ones work well and are a great value.
For alittle more than you budgeted for you can get 5 full metal mags that feed well.
Hop up rubbers: go guarder clear....cheap and work really well with your targeted FPS
If you have any other questions, pm me and I'll reply as quick as I can
PS: Stick with airsoftparts.ca Best service you can get and local aswell!!