see you are in a predicament. if that is your website, i think you have some good stuff first off. second, there are no action sports shots which is like a whole new ball game. not saying you can't do it, just looks like you haven't or don't do it often.
on another note, are you planning to shoot the good riders? or just the groms with their parents money who want to blow up their facebook winter 12-13 album? or just anyone in the park good or bad? usually, at least all of the good riders i know, already have a group of people and connections if they want some pics or videos usually for free.
my suggestions would be to hit up the park and lap it early when all the real riders are out, talk to them and ask if you can take some pics with them, publish some free stuff, get their info get some contacts. that might allow you to get some shoots set up. if it was me, and someone came up and asked if i was down to do a photo shoot for 150, i would say no unless it was someone big whose work i have seen and know they can do an awesome job. i feel like you need some work to back your requests so people can say "damn, id pay to have him take pics for me"