Anacondas are not expensive. Yellow anacondas are usually $125-150. Granite morphs are more. Green anacondas are about.. oh.. $150 maybe a bit more.
You have to check your local and state laws before considering an anaconda. Condas are not beginner snakes, and not a good second snake either. Yellow anacondas stay smaller than greens (males average 6-8' females 10-12') Green anacondas are the heaviest snake species in the world.
Anaconda babies are usually pretty defensive and nippy. If they are worked with consistently many will tame quite nicely, but this is not a guarantee. They can be aggressive.
There are usually a number of ads for anacondas on kingsnake.com classifieds and fauna classifieds.