I'm going to also advise on IKEA. They have many types of beds for kids at really great prices and frankly I don't think they're bad quality. What I like most about them for very young children is that you can configure it so that they are pretty low to the ground so you don't have any worries about them falling out, or when it's time, they don't have any problems getting in and out when they need to go potty in the night.
I got both of my kids first beds there and they're daybeds because we have a small house and no game room. They need their toys in their rooms and enough room to play with them. I also didn't get a box spring so they are low to the ground. IKEA has these boards that you use instead of a box and it doesn't make the mattress higher.
When I was looking I also ran across some really great deals at Bombay Kids. They are not usually really cheap, but they will often put their furniture that they're discontinuing on sale for amazing low prices. I almost bought one there.
And one other thing, a couple weeks ago I was in Pier 1 Kids by Stonebriar Mall and they're going out of business and everything, including all their furniture was on sale for half price. By now, if there's anything left it's probably even cheaper.
Good luck.