Jackson's can be tough to find as Captive Bred (CB). A lot of the ones on the market are Wild Caught (WC), meaning that they were wild animals that were captured and shipped to the US for the or trade - this is very hard on the chameleon and WC chameleons often have health issues. If you are new to chameleons, I strongly recommend that you spend the extra money to be sure your Jackson's is CB.
Have you looked at FL Chams? They often have Jacksons available. Don't be afraid of shipping, but definitely be suspicious of a cheap Jackson's. I would expect to pay between $75 and $150 from a commercial breeder.
Jackson's are just the best. My Jax Ferdinand was an amazing chameleon. They are a smaller cham but can be very active and have more relaxed personalities. You'll still want a full sized set up for a Jax (24x24x48) and you'll definitely need a misting system - they need a lot of water.