BTW: For those working on the electronics i noticed that the link for the Raspberry is wrong. The current model of Raspberry Pi is the "Raspberry Pi 3 Model B".
Here are some links to buy the RP Model 3 B:
Also the Arduiono Mega 2560 can be found for much less than $45.00 in the US. I bought my last one for around $15.00 at MicroCenter. The cheaper ones appear to be third party copies of the genuine Arduiono branded boards so there may be some risk there. I'm running a version 1 FC using the cheaper brand and I haven't noticed any issues with it.