yes look on craigs list, especially is you live in or live by a rich area you can come across alot of good deals on tanks. if you find a good deal on a glass tank make sure the silicone thats holding it together isnt rotting away. and if you find an acrylic tank make sure its not too scratched. if it is scractched but its at a really good price you can always work on it and remove the scratches as long as they arent too deep. same goes for glass, its pretty easy actually, you can contact me if thats every the case, ive done it many times on both glass and acrylic. im fairly new at this myself but if you're looking to do reef you might want to get a tank thats already drilled... or you can buy new online, glasscages.com has good prices on all types of tanks even their custom tanks. they have horrible customer service but if you get something simple through them and inspect every inch of the tank before taking it off the truck then you should be ok
good luck