As said id be looking for a full 4130 cromo frame and fork
As your likely to be riding skateparks and some street (street is tough on the body!) look at reputable brands like S&M, FIT, We the people, Kink, Sunday etc…
My S&M WTF is coming up for 13 years old now and cost almost 2k in 2011 due to the build components and in that time all ive needed to replace is tyres
In nearly 40 years of riding bmx the one thing ive learnt is not to buy cheap frames and components
Whats your budget? there are some great 2nd hand deals out there for lightly used bikes