Well, not even a hack, but hope you guys will like it
People got to easy way to abuse current Community Robot Factory 50% discount (robocraftgame.com/christmas-sale/)

If you want to build a megabot or have a lack or RP and wish to buy parts half a cost, you have solution: search any required part in Community Robot Factory or ask a friend to post one - so he get income after your purchase. It is simple.

People here say it works and I also got few megaparts that way.
So cheers and use until closed
robocraftgame.com/forums/topic/use-crf-to-purchase-any-part-50-cheaper