We have purchased a few pieces of furniture over the last 10 years and have learned a few things. Furniture that is made from a soft wood, like pine, or furniture that has to be assembled will not stand the test of time. We purchased a nice maple bunk bed for our oldest son when he was 3. The bed was manufacutred by Stanley Furniture. It was definitely more expensive than other beds we could have purchased, but when we consider how great it looks after 6 years of tough love by our son, it was worth every penny.
Pine furniture we bought around the same time looks completely beaten up and gets dented and nicked every time it comes in contact with a toy or a person. With 3 boys in our home, this means that most of our furniture takes a beating.
Even furniture we've purchased that has hard wood veneers does not hold up as well as high quality, hard wood furniture.
We recently purchased another bed when our baby moved out of his crib and into a bed. We looked at Costco, Dania, JC Penny Home, Levitz, Wickes and several other furniture stores. What we found was that most furniture is now made with very few solid wood pieces or is made with soild soft woods. We had a very hard time finding an inexpensive piece of furniture that wasn't made from MDF covered in veneers.
So, we bit the bullet and purchased another Stanley bed, but I know it will be the last bed we will have to buy our son. The bed was part of the Young America line of furniture by Stanley and we were able to purchase it at Paul Schatz in Lake Oswego, Oregon.
I realize you are probably looking to spend a lot less on a bed, but you definitely get what you pay for. My suggestion would be to check Craigslist.com or your local paper's classified ads. Also, put the word out that you are looking for a high quality used bed. I have a friend who did this and a friend of a friend happened to be getting rid of 2 Ethan Allen twin beds for $200 for the set!
I would pick a high quality used bed over an inexpensive, cheaply made, new bed any day. I hope this helps.