IKEA is cheap, modular and with a lot of options. Replace it when they're older with better quality stuff.
I bought an entire kids bedroom set at Bel Furniture for $500 excluding the mattress. I've had it for a year and it really is good quality stuff.
I will follow my futile attempt at humor with this... Rooms to go is offering a buy one get one free $100 gift card promo, look into it.