Most of my bubblers were around 40 bucks, you can definitely find some decent ones for 20 to 30 depending on your location. And I would definitely recommend a local head shop if that's your price range. Try to get something that cheap online, and you're likely going to get very poor quality work. At a head shop you can still find some gems for very low prices, and you get to give it a close inspection first and make sure it's worth your money.
This is a small bubbler, only $20
This one is bigger, paid $40
I hope you find what you're lookin' for.