Thing have become cheaper in my opinion. Companys like hobbywing have the xerun series or extreme stock esc that are only about 60quid and i think they are an awesome peice of kit.
Motors are still similar prices to what they used to be so expect to pay 50-90quid for a top spec one.
What i would auggeat is go to the place you are planning to race and ask the people racing what they use.
Are you going to.use the pro4 or are you looking at a new chassis kit aswell.